Liberians want the US to intervene

"The exact steps that could be taken are still under review," White House spokesman Ari Fleischer said after President George W Bush met his top security aids on Tuesday.

"We're actively discussing how best to support the international efforts to help Liberia return to peace," said Mr Fleischer, who did not rule out sending US troops.

The meeting followed calls by UN Secretary Genera Kofi Annan urging US to participate in a multilateral force in the war-torn west African country.

Mr Fleischer denied suggestions that the US military were reluctant to get involved in Liberia because its troops have been stretched by deployments in Iraq and Afghanistan.

"It's not a question of being stretched too thin, it's a question of what is the best way to accomplish a mission. That's what the president's focus will be," he said.

It's the worst humanitarian situation I've seen in any war zone Magnus Wolfe-Murray, Merlin

Liberians have been demonstrating outside the US Embassy in the capital, Monrovia, vowing to go on hunger strike until the US intervenes to end the conflict.

Meanwhile, aid workers said they were struggling to help thousands of people displaced and injured by the fighting.

Liberia is Africa's oldest republic, founded in 1847 by freed African American slaves. It has had close ties with Washington.

Peace force

The UN is actively seeking to build the peacekeeping team on the ground with action being led by the British ambassador to the UN, Sir Jeremy Greenstock.

Mr Greenstock said there were "big obstacles on the way to peace" for the war-torn Liberia.

Liberia and America have historical ties

His proposal would have West African nations give 3,000 troops for what would be a 5,000-strong force to separate forces of Liberian President Charles Taylor and rebels.

West African leaders have in turn asked the United States to contribute 2,000 troops to the peace force and want President Bush to decide before he makes his first African visit next week.

Last week, Mr Bush urged President Taylor to step down "so that his country can be spared further bloodshed".

On Tuesday, Mr Greenstock for the first time publicly raised the possibility that President Taylor's going into exile could be a means to end the violence.

'Death and suffering'

In Monrovia's diplomatic quarter, workers from Medecins Sans Frontieres (MSF) set up long white tents to treat thousands of people for bullet wounds and cholera.

Up to 250,000 people fled to the city centre during two rebel assaults this month, which killed about 700 people, reports Reuters news agency.

But some are now returning home after four days of relative calm.

"It's not an epidemic yet, but it's the worst humanitarian situation I've seen in any war zone," said Magnus Wolfe-Murray of British-based medical charity Merlin.