Three protesters killed as Yemen troops open fire

The violence began with a pre-dawn raid on a central square in the capital, Sanaa, where thousands of pro- democracy protesters have been camped out for the past month to demand the removal of president Ali Abdullah Saleh, who has been in power for 32 years.

Doctors and eyewitnesses said security forces surrounded the square with police cars and armoured personnel carriers shortly after midnight and began calling on protesters through loudspeakers to go home. At 5am, the security forces stormed in, firing tear gas and live ammunition.

One protester died from a bullet to the head, which may have come from a sniper on the rooftop of a nearby building. Abdelwahed al-Juneid, a volunteer doctor working with the protesters, said about 250 people were wounded.

"We were performing dawn prayers when we were surprised by a sudden hail of bullets and tear gas," said Walid Hassan, a 25-year-old activist. "The protesters began throwing rocks at security … it was total mayhem, a real battlefield."

A few hours later, another protester was shot dead in a nearby street. Eyewitnesses said he was also shot by a sniper.

In the port city of Mukalla, in the south-eastern province of Hadramout, a 15-year-old was gunned down when security troops fired on protesters. Twelve people were wounded in similar violence in Yemen's southern province of Taiz.

Yemen's president Saleh appears to be one of the Arab leaders most threatened by the regional unrest inspired by pro-democracy revolts in Egypt and Tunisia. Demonstrators are also demanding jobs and greater political freedoms.

Saleh has tried to calm protesters by proposing that the government creates a new constitution guaranteeing the independence of parliament and the judiciary - but protesters have said it is too little, too late.

Yesterday's raid in Sanaa came after Yemen's largest demonstrations in a month on Friday were met by police gunfire that injured at least six protesters and seemed certain to fuel more anger against the deeply unpopular Saleh.

Hundreds of thousands of protesters gathered in Yemen's four largest provinces, ripping down and burning Saleh's portraits in Sheikh Othman, the most populated district in the southern port city of Aden.

In the capital, thousands of women joined the demonstrations - a startling departure in a deeply tribal society where women are expected to remain out of sight.

By Friday evening, protesters in Sanaa had expanded the area of their sit-in encampment, further angering authorities and leading to clashes with plainclothes security men.Protesters said the security men were carrying sticks, knives and iron rods. Four protesters were injured.

Yemen was chaotic even before the demonstrations began, with a resurgent al-Qaeda, a separatist movement in the south and a sporadic Shiite rebellion in the north vexing the government, which has little control outside major urban areas.

In Washington, a top White House aide told Saleh on Friday that the United States welcomed his steps to resolve the crisis and urged opposition groups to heed calls for talks.

"All sectors of the Yemeni opposition should respond constructively to president Saleh's call to engage in a serious dialogue to end the current impasse," White House counter-terrorism adviser John Brennan told Saleh.

The US fears that should Saleh be overthrown, then that might lead to a power vacuum which would be exploited by Islamist militants in the Arabian peninsula state, from which al-Qaeda has launched attacks on western and Saudi targets. Saleh is a Zaydi Shia Muslim, or Fiver, who has kept up ties with Iran.

Protesters are frustrated by rampant corruption , high unemployment in a nation where 40 per cent live on 1 a day or less and a third lack food.