Liberians have nowhere safe to flee to
Supplies of safe drinking water have run out in most parts of the Liberian capital, Monrovia, increasing fears that cholera and other illnesses could spread rapidly.
The water supply was cut by an attack on a water pumping station five days ago and most storage tanks are now empty.
The battle for Monrovia, now into its sixth day, is showing no signs of easing with rebels in control of the port area, but a strategic bridge back under government control.
As the battle continued on Thursday, West African, United States and United Nations officials discussed plans to send Nigerian peacekeepers to Liberia in the next week.
Aid workers says the violence is preventing them reaching the thousands of Liberians crowded into churches, schools and other temporary shelters.
The main hospital in Monrovia is being overwhelmed by the wounded from this week's fighting.
Waiting for the peacekeepers
The BBC's Paul Welsh in Monrovia says the loss of clean drinking water supplies will make matters much worse for civilians.
Cases are already being reported of cholera and other diseases blamed on the unsafe drinking water.
People are queuing for food... aid agencies warn of disaster
Meanwhile, officials from the West African region, the United Nations and the United States met in neighbouring Sierra Leone to discuss plans to send more than 1,000 Nigerian peacekeepers.
The plan is also being discussed by the UN security council in New York.
The UN's special representative to Liberia, Jacques Klein, told the BBC that the Nigerian peacekeepers could be on the ground within three days.
However the plan was met with some scepticism in Liberia.
Liberian Defence Minister Daniel Chea said he would believe in their deployment when he saw them arrive.
Troops were first pledged more than a month ago.
Pressure on Washington
A top aide to President Charles Taylor in Ghana, Lewis Brown, said the embattled Liberian leader would leave the day the Nigerian troops arrive, reported Associated Press news agency.
The head of the West African regional grouping Ecowas, Mohamed ibn Chambas, told the BBC he hoped all Liberians would respect a ceasefire.
He said the United States - which is under increasing pressure to send troops to the county - would help pay for the deployment and had already pledged $10m.
Reports say American military helicopters have flown into Monrovia, bringing reinforcements to protect the US embassy compound and to ferry out 17 aid workers and foreign journalists.
Several hundred people are believed to have been killed in the past few days.
Corpses have been piled outside the US embassy in protest at the lack of
British aid agencies have joined the appeal for Europe and the US to send peacekeepers to the war-torn country.
Signed by a several organisations, including Save the Children and Christian Aid, a statement accused President George W Bush of "prevaricating".
"The rest of the world has stood by as Liberia has disintegrated
once more into chaos," they said.
Former US envoy to Africa Jesse Jackson has also criticised President Bush for not sending troops to Liberia.
"Liberia's been a long time ally, and we are on the verge of betraying Liberia for a second time. The silence of Secretary [of State Colin] Powell, security chief [Condoleezza] Rice and Mr Bush is deafening," he told the BBC's World Today programme.
Aid agencies have warned of a humanitarian disaster in Monrovia as they try to help some 250,000 people who have nowhere to live after fleeing to the capital.