The lone surviving gunman of the 2008 Mumbai attacks was sentenced to death yesterday, but any execution will only happen after a lengthy appeal process is completed, legal experts say.

In a widely expected decision, Mohammed Ajmal Amir Kasab, 22, a Pakistani national, was given the death penalty after a year-long trial at a prison court in the city he attacked nearly 18 months ago.

The question now is when, or even if, India will actually send him to the gallows.

India has not carried out an execution since 2004 and has hanged two people since 1998. The Supreme Court says the punishment is reserved for the "rarest of rare" crimes.

The last available statistics show 308 people were on death row at the end of 2007.

P. Chidambaram, the Indian Home Minister, said last year that pleas for clemency to the president would be considered carefully case by case, but refused to specify a time-frame for any decision.

He added prosecutors would appeal against the acquittal of two Indian suspects over the 2008 attacks.

Fahim Ansari and Sabauddin Ahmed were freed after Judge M.L. Tahaliyani gave them the "benefit of doubt."

They had been accused of helping the gunmen with logistical support, by providing hand-drawn maps of Mumbai.

Meenakshi Ganguly, South Asia researcher at Human Rights Watch, said Kasab's case was likely to be caught up in the lengthy -- and potentially open-ended -- legal process.

"They have to go turn by turn, so there are others ahead in the queue," she said.

A senior researcher at Amnesty International added, "If the government follows that principle, as they said they would, it's unlikely we will see Kasab's execution very soon."

Nevertheless, observers said Indian authorities could come under intense pressure to fast-track the case, amid lingering public outrage at the Islamist insurgent attacks, which killed 166 and wounded more than 300.

Residents of Kasab's home village condemned his conviction, saying it was the result of a conspiracy against Pakistan.

"He is Pakistani, that's why he is going to be hanged," said Mohammad Ramazan, a retired village school teacher.

"It's a conspiracy."

Pakistan's Foreign Ministry said its legal experts would examine the Indian court's detailed judgment.

"Pakistan has strongly condemned the horrific Mumbai attack. It is important that culprits are brought to justice," Abdul Basit, a ministry spokesman, told a briefing.