Yemen's veteran President, Ali Abdullah Saleh, was wounded by shellfire as his presidential palace came under attack amid the country's brewing civil war Friday.

Mr. Saleh, who has held office for nearly 33 years, was praying in a mosque in the fortified palace compound in the capital, Sanaa, when it was struck by at least two shells, killing three guards and the imam.

The President escaped with light injuries "to the back of his head," said Western diplomats and government officials, but the Prime Minister, Ali Mohammed Mujawar, and Speaker of Parliament, Yahya al-Rai, were more seriously hurt. Rashad al-Alami, the Deputy Prime Minister and a leading pro-Western voice in the Cabinet, was said to be in a critical condition.

In an audio statement broadcast late Friday on state television, Mr. Saleh, who was being treated at the defence ministry hospital in Sanaa, said, "I am well, in good health," and added the bombardment had killed seven people.

Two more protesters were killed in Yemen's second-largest city of Taiz, just days after 50 people died when government forces stormed a protest camp.

In a major reverse, it was reported that demonstrators were holding a city square, which they had named Freedom Square.

The government was quick to blame the powerful Ahmar family, leaders of the Hashed tribal federation, for the attack on the palace. Its militiamen have been engaged in bloody street clashes with regime forces in Sanaa.

Raising fears of a major escalation in the violence of the past two weeks, in which more than 100 people have been killed, the government promised retribution. By nightfall, several Ahmar family homes had been shelled.

Mr. Saleh has clung to power for four months in the face of protests by hundreds of thousands of people.

As opposition television reported he had been killed, opposition supporters at the main protest camp erupted in celebration, dancing and chanting.

The President has authorized the brutal suppression of anti-government demonstrations, which has tarnished his credentials in the West, where he was viewed as an ally against al-Qaeda in Yemen.

But the standoff between Mr. Saleh and his people has become complicated by the confrontation with the Ahmars, who are supporting the protesters even though the family is almost as unpopular as the President on the streets.

Last week, after reneging on a U.S.-backed plan to hand over power, Mr. Saleh launched an attack on the home of Sadeq al-Ahmar, the titular head of the Hashed. Since then, thousands of armed tribesmen have descended on the capital to give support to the Ahmars.

Further bolstered by defections within the army, the Hashed took their battle from their strongholds in the north of the city this week to the prosperous southern suburb of Hadda, home to diplomats, government officials, businessmen and the President.