British Honorary Consul in Bissau, Jan van Manem

President Joao Bernardo Vieira was forced to flee his palace when it was set on fire by rebel forces led by the dismissed army chief, General Ansumane Mane.

President Vieira is thought to be seeking asylum in Portugal

He has taken refuge in the embassy of the former colonial power, Portugal, and some reports say he is seeking asylum in Portugal.

A brief statement from President Vieira's chief of staff said his troops had surrendered to General Mane's rebels in view of the deteriorating security situation and in the interests of the country.

The announcement came as rebel forces surrounded the presidential palace, having moved into the capital, Bissau, under cover of darkness.

Eyewitnesses in the capital, Bissau, say at least 100 people have been killed in the fighting, and there are reports of widespread looting and bodies lying in many streets.

The Portuguese news agency said scores of civilians were killed when a shell hit a crowded church mission where people had been seeking shelter.

The UK honorary consul in Bissau, Jan van Manen, told the BBC that despite the violence the mood in the capital was euphoric with the news of the president's fall from power.

"The military, who appear to be fairly disciplined, are now in the streets of Bissau controlling the security of everybody," he said.

February pact broken

The violence breaks a shaky truce that had left the capital divided for nearly a year.

It followed last June's army mutiny, which began when the president dismissed General Mane over allegations that senior army officers had been smuggling weapons to separatists in neighbouring Senegal.

Under a truce agreed in February, a national unity government had been sworn in and Senegalese troops supporting President Vieira had left the country.

They had been replaced by 6,000 peacekeeping troops from the West African intervention force, Ecomog.

The BBC's Africa reporter, Caroline Hawley, says the rebels are reported to have been angered by the failure of Ecomog to disarm President Vieira's presidential guard.

Portuguese television has shown pictures of residents of Bissau celebrating the removal of President Vieira.