At least 20 patients believed to be suffering from Ebola have fled a quarantine clinic in Liberia after protesters reportedly broke down the doors and looted the building, sparking fears of a serious health risk.

The incident occurred in the Liberian capital of Monrovia in the West Point 'slum' on Saturday evening. Blood-stained bedding was among some of the items taken from the centre, which officials say poses a serious infection risk.

Tolbert Nyenswah, the assistant health minister, said protesters were apparently displeased that patients were being brought in for treatment from different parts of the capital. Other reports suggested they were concerned Ebola is a hoax.

West Point residents went on a "looting spree," stealing items from the clinic that were likely infected, a senior police official told the Associated Press. The residents took medical equipment, mattresses and sheets that had bloodstains, he said.

"All between the houses you could see people fleeing with items looted from the patients," the official said, adding that he now feared "the whole of West Point will be infected."

West Point is home to at least 50,000 people. The patients' whereabouts remain unknown.

The break-in comes just a day after crowds converged on a burial team who arrived in West Point to collect bodies of suspected Ebola victims, while chanting: "No Ebola in West Point".

Earlier this week, Liberia health care workers administered three doses of the rare, experimental drug ZMapp to three doctors suffering from Ebola. Dr Billy Johnson, chief medical officer of John F. Kennedy Medical Centre in Monrovia, said a six-day treatment programme began on Thursday.

Liberia has the highest death toll from Ebola to date, with 413 succumbing to the virus. At least 1,145 people across West Africa have died so far since the outbreak began in February.

The drug has already been administered to two American healthcare workers and a Spanish priest, all previously working in Liberian hospitals.

The US healthcare workers' health has since improved but the Spanish priest died.

Up to 90 per cent of Ebola victims die - a fatality rate so high that the US Centers for Disease Control and Prevention (CDC) classifies the illness as a category a "bioterrorism agent" - although the current outbreak fatality rate is near 60 per cent.