Government fighters have fired shots in the air to prevent hundreds of Liberians crossing into the rebel-held port area of the capital, Monrovia, to look for food.
A small contingent of marines have arrived in the capital
People in the capital are desperate for food, especially in government areas where rice is reported to cost L$100 (US$2) compared to L$5 (10 US cents) in rebel-held areas.
The humanitarian situation seems to be better in rebel-controlled parts of the city because they have been distributing the stocks of food which were in the port's warehouses, reports the French news agency, AFP.
Meanwhile a small contingent of US marines has been flown into Monrovia to liaise with the commanders of the West African Ecowas force, who have already set up their headquarters.
US President George W Bush, told journalists at his ranch in Texas:
"This is all part of determining what is necessary to help Ecowas... to go in and provide the conditions necessary for humanitarian relief to arrive, whether it be by sea or by air."
They are also expected to for a larger American force, which the US says it will send when President Charles Taylor resigns.
There has been some confusion over whether Mr Taylor will step down and take up an offer of exile in Nigeria.
Reuters news agency says South African President
Thabo Mbeki told a business forum on Wednesday he was planning to fly to Monrovia on Monday to attend a ceremony marking the handover of power by embattled President Taylor.
He said agreed to make the trip after a request from Ghanaian President and Ecowas chairman John Kufuor.
But earlier a Nigerian presidential spokesman said Mr Taylor was only willing to leave if he was promised immunity from prosecution.
A United Nations-backed war crimes tribunal has issued an international warrant for his arrest for his alleged role in the brutal 10-year civil war in neighbouring Sierra Leone.
First patrols due
An estimated one million people are in urgent need of humanitarian aid, as ships have not been able to dock since the rebels seized the port during the past month of fighting in Monrovia.
On Tuesday, the rebels promised West African peacekeepers that aid agencies could use the port in the capital, Monrovia, to deliver badly needed supplies of food, water and medicine, West African peacekeepers said.
The Chief-of-Staff of the West African peacekeeping force, Ecomil, Colonel Theophilus Tawiah told BBC News Online that the rebels had given this commitment at a meeting in rebel-held territory near the port.
However, some rebel commanders say they will remain in the port until Mr Taylor steps down.
Aid agencies say that access to the port would be a massive boost for their humanitarian effort.
"If (peacekeepers) can protect the port then it will let us get fuel and provide access to the other half of the city," said Magnus Wolfe-Murray from the British-based charity Merlin.
The United Nations has launched an appeal for almost $70m to provide food, shelter, medical care and assistance to civilians affected by the fighting.
Ecomil is due to start its first patrols in Monrovia later on Wednesday, Colonel Tawiah said.
So far, they have remained at the Robertsfield airport, some 40km from the city centre.
But our correspondent says their arrival has already changed the atmosphere in the city.
On Tuesday government fighters were seen embracing rebel gunmen on one of the bridges that had been the front line of the conflict.
FORCE FOR LIBERIA
First of 1,500 Nigerian troops arrived on Monday
2,000 West African troops to follow
UN stabilisation force to be deployed by 1 Oct
Both groups said they wanted to stop fighting.
Liberia has asked the International Court of Justice in The Hague to cancel the war crimes arrest warrant against Mr Taylor.
But US Defence Secretary Donald Rumsfeld said in Washington that there was no suggestion that the charges against Mr Taylor might be dropped.
"Everyone except that individual seemed to feel it would be best for the country if he would leave," Mr Rumsfeld added.