The US President is holding a conference with major world leaders to discuss the ebola outbreak, which he says the world is not doing enough about.

Barack Obama said he plans to pressure some countries into taking firmer action to slow the spread of the disease.

His comments came as it was revealed that the United States is establishing a rapid-reaction team to help hospitals whenever a case of ebola is discovered.

More than 4,400 are now known to have died of the virus across Sierra Leone, Liberia and Guinea, with more than 8,000 infected.

However, world health experts say that the number of people being infected will reach 10,000 a week within two months.

US officials were forced to admit on Tuesday that they had not done enough to limit the disease before the death of a man who had travelled from West Africa.

Centers for Disease Control director Tom Frieden unveiled a series of steps designed to stop the spread of the disease in the US, including the rapid response force and increased training for healthcare workers.

He made the move after being told by many hospital staff that they lacked the training needed to deal with the virus.

Mr Freiden said about the rapid reaction force: "I wish we had put a team like this on the ground the day the patient - the first patient - was diagnosed.

"That might have prevented this infection. But we will do that from today onward."

A nurse who caught ebola while treating the first victim to die on US soil released a statement on Tuesday thanking people after being given a transfusion containing antibodies.

Mr Obama, speaking at a meeting of world defence ministers, said he planned to hold a video conference with British, French, German and Italian leaders to discuss ebola and other international issues.

The World Health Organisation said the share of people infected who are dying from the disease had now risen to 70%.

Anthony Banbury, head of the United Nations mission for ebola, told the UN Security Council that the global response to the crisis must meet critical goals by 1 December "or face an entirely unprecedented situation for which we don't have a plan".