Liberia was desperately searching for 17 Ebola patients Monday who fled an attack on a quarantine centre in the capital Monrovia, as the outbreak appeared to overwhelm authorities in west Africa's worst-hit nation.

Searches of the teeming West Point slum have so far failed to turn up any of the missing victims as neighbouring Guinea said a wave of sick Liberians had begun crossing the border, which it had officially closed 10 days ago.

Club-wielding youths raided a medical facility set up in a high school in the dense-populated Monrovia slum on Saturday, some shouting "there's no Ebola", echoing wild rumours that the epidemic had been made up by the West.

Officials are considering sealing off the area -- home to 75,000 people -- to stop the nightmare scenario of people with the highly contagious disease wandering the city where unburied corpses have lain abandoned in the streets.

Information Minister Lewis Brown said: "All those hooligans who looted the centre are now probable carriers of the disease.... They took mattresses and bedding that were soaked with fluids from the patients. To quarantine the area could be one of the solutions.

"We run the risk of facing a difficult-to-control situation," he warned.

Community leaders, however, said the patients have long gone.

Wilmont Johnson, head of a youth association in West Point which organised a search for the patients, told journalists Monday that "those who saw them passing told us that they have gone into other communities".

The head of the Health Workers Association of Liberia, George Williams, said of the 29 patients in the raided unit "all had tested positive for Ebola" and were receiving preliminary treatment before being taken to hospital.

Fallah Boima, whose son Michel was among the patients who fled, told AFP: "I am afraid that he could die somewhere and I will not know."

Outside the capital in Caldwell, relatives of the dead criticised the government for the slowness of its response, claiming that bodies were being left uncollected there for days.

Sheikh Idrissa Swaray, the father of one victim, slammed the way the government was handling the crisis as "completely wrong".

He said in one case a man had died and his wife, possibly infected herself, had run away.

"We don't even know where the wife has gone and the body is still here. Three days now and the body has not been taken."

Liberia already has the highest death toll in the epidemic, which has killed at least 1,145 people across west Africa since the start of the year. Its toll of 413 dead last week overtook that of Sierra Leone and Guinea where the outbreak began, despite a state of emergency being declared.

Wave of sick Liberians

Dr Sakoba Keita, who is heading Guinea's fight against the epidemic, told AFP that a wave of sick Liberians were crossing the border in the Macenta district in the south of country, where Ebola had up till now been on the wane.

"We are very worried about this situation of sick people arriving from Liberia. We are having more and more suspected cases in the area," he said.

A Guinean military doctor on his way to the border said: "We are doing everything we can but there is a huge gulf between the rhetoric and the situation on the ground."

Guinea announced 10 days ago that it was closing its borders with Liberia and Sierra Leone, a forested region notoriously hard to police, and it was unclear how the sick patients made it into the country.

AU, Cameroon closings

Now Cameroon also has closed all its land, sea and air borders with its neighbour Nigeria, and will restrict travel to other affected countries, a government spokesman told AFP on Monday.

The virus has claimed four lives in Nigeria, Africa's most populous country. So far Cameroon has escaped unscathed.

The new travel bar comes as the World Health Organization said it had set up a task force with global airlines and the tourism industry in an effort to contain the spread.

The outbreak has also led the African Union to cancel its summit scheduled for September 2 in Ouagadougou, although Burkina Faso to date has been unaffected.

There is no known cure for Ebola, a haemorraghic fever which can be spread through bodily fluids including blood and sweat.

The epidemic is the worst since the virus first appeared in 1976 in what is now the Democratic Republic of Congo. It has also claimed 380 lives in Guinea and 348 in Sierra Leone, according to WHO figures released on August 13.