THE US has announced it is to send 3,000 troops to help tackle the Ebola outbreak as part of a ramped-up response including a major deployment in Liberia, the country where the epidemic is spiralling fastest out of control.

The US response to the crisis, unveiled by President Barack Obama, includes plans to build 17 treatment centres, train thousands of healthcare workers and establish a military control centre.

The World Health Organisation (WHO) has said it needs foreign medical teams with 500-600 experts as well as at least 10,000 local health workers, numbers that may rise if the number of cases increases, as it is widely expected to.

So far Cuba and China have said they will send medical staff to Sierra Leone. Cuba will deploy 165 people in October while China is sending a mobile laboratory with 59 staff to speed up testing for the disease.

But Liberia is where the disease appears to be running amok. The WHO's Director-General Margaret Chan has said there is not a single bed available for Ebola patients there.

Liberia, a nation founded by descendants of freed American slaves, appealed for US help last week.

A UN official in the country said her colleagues had resorted to telling locals to use plastic bags to fend off the killer virus, for want of any other protective equipment.

Medecins Sans Frontieres, the charity that has been leading the fight against Ebola, said it was overwhelmed and repeated its call for an immediate and massive deployment.

"We are honestly at a loss as to how a single, private NGO is providing the bulk of isolation units and beds," MSF's international president Joanne Liu said in a speech to the UN in Geneva, adding that the charity was having to turn away sick people in Monrovia.

Mr Obama, who has called the epidemic a national security crisis, has faced criticism for not doing more to stem the outbreak which the WHO said had killed more than 2,500 people out of 5,000 cases in West Africa in an "unparalleled crisis".