AT first glimpse, it looks like a popular protest. A tide of thousands of people standing close together amid the blitzed buildings in Yarmouk refugee camp in Damascus.

But the faces in the crowd tell a different story. Pale and gaunt with staring eyes, this is a weakened population queuing for food parcels at the single aid distribution point for the United Nations refugee agency after almost a year spent living under siege.

The photograph has become one of the defining image of the Syrian civil war.

Graphic pictures and video showing the victims of bullets, shellfire and beheadings in Syria are spewed daily across social media and Internet sites, but it is this scene that horrified the world.

Since the photograph was released by the UN last week, it has prompted condemnation from world leaders, and comments of heartfelt despair from United Nations officials, one of whom described Yarmouk as “apocalyptic”.

It has put the Damascus neighbourhood on front pages of newspapers across the globe.

However for the estimated 40,000 people in the predominantly Palestinian area Yarmouk – trapped by government troops – life is still a daily battle against starvation, disease from dirty water, air strikes and mortar fire.

Two brothers of Rania Marjeh, 39, a former resident of Yarmouk who now lives in Britain, were part of the multitude queuing for food on the day the photograph was taken. It is one of the last things they did together before the younger of the two, Mohannad, 25, was killed in mortar attack on Valentines day.

His death and the futile battle by his friends to save him in a place where basic medication and even electricity are not available lays bare the reality of a life under siege.

“Mohannad died three days after he was hit by a mortar as he sat on the back of a bicycle being ridden by our brother Mazen, 36,” Mrs Marjeh told the Telegraph. “The Geneva II talks were under way. There had been a lull in the fighting and everyone thought there was a de facto ceasefire in place.”

He had wounds to his head. A piece of shrapnel had torn through his abdomen. He was carried to one of the few field hospitals in Yarmouk. But after months of total blockade and no electricity, the hospitals are essentially first aid clinics; sparse rooms with a hospital bed and what rudimentary medical supplies remain.

Mrs Marjeh said: “Mazen and friends of Mohannad donated blood and the volunteers at the clinic were able to bandage up the wound on his abdomen. But they could not remove the shrapnel from his head wound or carry out any examination.”

Mohannad’s parents live outside the blockade by accident. They had intended never to leave their homes in Yarmouk. But one day last year, they went to visit relatives outside of the camp to celebrate the Muslim holiday of Ramadan.

When they tried to go home, government soldiers and pro-regime paramilitaries blocked them at every road, forbidding their return. The siege had begun, and they were separated from Mohannad and Mazen who remained trapped inside.

When word reached them of Mohannad’s condition, they tried desperately to get access to see him, but were again banned refused entry. They were also advised not to try to take Mohannad out. He was too weak to endure the arduous and dangerous smuggling route, and, as he had defected from his military service, the family was told that should they being him to a government checkpoint, he would be arrested no matter his condition.

Phone signal was patchy and the parents were instead forced to wait torturous hours for the few moments that Mazen was able to reach them with updates.

After two days, Mohannad fell into a coma.

“His heart stopped but they managed to resuscitate him after someone turned up with a dose of adrenalin. But from then on he was not able to breathe unassisted,” Rania said.

“We were told he was on life support. We first imagined this was one of those high tech machines that they had managed to hook up to a generator.

"But we were later told that the life support machine consisted of a hand pump and 8 of his friends taking it in turns to pump air into his lungs.”

He died the next day. “It is so difficult knowing that having a CAT scan might have saved his life. I know that publishing something about him might cause some trouble for my family,” said Rania, referring to possible harassment or arrest by pro-regime groups. “But we owe it to Mohannad to share what happened to him. We have to spread the word of what is happening in Yarmouk.”

Yarmouk was once a sparsely populated district of south Damascus that accommodated refugees fleeing the fighting in Palestine. Over time, the camps were replaced with cement block homes, making a self-contained city close to the heart of the Syrian capital, with a population of some 160,000 by 2011.

The main thoroughfare, Yarmouk street, which is the devastated area pictured in the photograph, was a bustling high street, like “Oxford street in London” according to Rania and other residents.

Ziad, 24, who is from Yarmouk and who spoke using a pseudonym, said: “Yarmouk street is where people with money in the area went to shop. There were international high street stores, including Benetton and Zara. I used to spend most of my time there, in coffee shops with my friends.”

The district, Ziad said, was a friendly working class place. Neighbours knew each other, and would pass time sitting on chairs in the street smoking shisha with each other. He often played football, went swimming or attended events at the cultural centre.

“Yarmouk was one of the last places in Damascus to join the revolution,” he said.

As uprising turned into war in other parts of the capital and cities and towns, homes and schools in Yarmouk became shelters for “up to one million” internally displaced persons (IDPs). “We essentially bribed the rebels not to come inside, instead using Yarmouk as a conduit to send food and medical aid to areas they already controlled.”

Located at the entrance to the southern Damascus suburbs where rebels from the Free Syrian Army had gained considerable control, Yarmouk then became a supply line for opposition fighters. Aware of this, the Syrian government began firing mortars on the camp, and paying the Popular Front for the Liberation of Palestine, a pro-regime faction in Yarmouk, to arm themselves inside the camp.

“The PFLP were in some ways doing a valuable job in managing camp security. They caught car bombs that were being sent into the camp by actors who were unhappy with how little we were participating in the revolution,” said Ziad. “But at the same time they aggravated the relationship with the FSA. They started fighting with rebels who were in neighbouring Tadamon district, sparking tit for tat kidnappings.”

In the summer of 2012, pro-government paramilitaries from the ruling minority Alawite sect who lived in Nisreen street, east of Yarmouk, opened fire on a mass anti-government demonstration killing ten people, including one seven-year-old boy.

The situation then deteriorated rapidly. Wanting to ensure that Yarmouk, the “gateway to the south” remained open to them, “more than 100 rebel factions flooded the area”, Ziad said.

The regime needed to cut the supply line through Yarmouk. Government troops and pro-regime militias encircled the area, and, by October 2012, the entrances to Yarmouk were only open two or three days a week.

From then on, the tragedies began to mount. As the fighting escalated, civilian residents of Yarmouk and internally displaced people bore the brunt of the violence. In December, the Syrian air force bombed a mosque that was housing families who had fled fighting in other parts of the country, killing dozens. Witnesses told the Sunday Telegraph the rebels had been hiding weapons in basement of the mosque, hoping the presence of civilians would be a deterrent to an air strike.

As Yarmouk became totally blockaded, markets and shops became empty and residents survived on what food supplies they had stored. Then even those ran out. Tanks were stationed at the main northern entrance, snipers picked off anyone attempting to escape from the west, and pro-regime militias patrolled the east and southern areas.

“My friends ring me up, crying because they are starving. They have nothing to eat,” said Ziad, who left Yarmouk shortly before the blockade was imposed. “I told them to break into my house and eat the canned food supplies I had. After that I had nothing to offer. I felt helpless.”

Rania said that for the past two months her brothers had been living on “a diet of cactus, weeds and spices cooked in water”.

Corruption was rife in the area, and, though the black market prices were desperately high, you could bribe soldiers for meagre supplies, residents said.

“Only the day before he was hit Mohannad had phoned up my parents with a huge shopping list of food and cigarettes. Rumours were abounding that the checkpoints would open,” said Rania. “When my mum asked him why he wanted so much he said it was for his friends who did not have any family left outside to help them.”

Children, the elderly, the sick and poor were the worst hit, and footage soon emerged showing their malnourished skeletal bodies. When people began to die, religious leaders in the area issued a decree allowing people to eat cats and dogs.

Pummelled by “barrel bombs” – containers loaded with TNT, air strikes and mortar fire for months on end, there was little left if Yarmouk.

On the January 31, after almost one year of siege, the United Nations managed to negotiate access to bring in 7,500 food parcels, with one parcel intended to feed a family for one week. Given the need, it was a negligible amount.

After a visit on Tuesday, Filippo Grandi, UNRWA, the refugee agency’s chief, described the “shocking” conditions of life he witnessed in Yarmuk. He compared the people flocking to the distribution point as “the appearance of ghosts”.

Thousands of people emerged from the rubble, shuffling towards the distribution point, too weak to fight each other for the parcels.

Rania said: “At first my brothers didn’t believe the news that food parcels had come. When they went the queue was unbelievable. But they managed eventually to get a parcel.”

“It hadn’t hit me how bad the situation was until my older brother Mazen and I were speaking the day after Mohannad died, and he said “at least he managed to taste bread again before he died.”

Only then did I realise how bad it was for my brothers. Now Mazen is in there alone and I can’t imagine how he is living.

“As Syrians, we used to pride ourselves that in our country no one should go hungry. Now there are a whole people, inside the capital city who are starving.”