The death toll from west Africa's Ebola outbreak has risen to more than 2,400 from at least 4,784 cases.

However, the World Health Organisation's director general Margaret Chan said that is highly likely to be an underestimate.

Ms Chan said the number of cases of the deadly viral disease is rising faster than authorities' ability to manage them.

She called for international support in sending healthcare workers, medical supplies and aid to the worst-affected countries of Guinea, Sierra Leone and Liberia.

Cuba is sending 165 doctors and nurses to Sierra Leone to help fight the outbreak, Cuba's health minister and the WHO announced this morning.

Ms Chan hailed Cuba's commitment to send the health professionals to the hard-hit west African country for six months.

She told reporters it was "the largest" made so far in the global fight to stop the deadly outbreak.

She said the three worst affected countries were also running low on "almost everything" - including personal protective equipment, basic medical supplies and body bags.

"Today there is not one single bed available for the treatment of an Ebola patient in the entire country of Liberia," she said.

The Ebola infection rate and death toll have been particularly high among health workers, who are exposed to hundreds of highly infectious patients who can pass the virus on through body fluids such as blood and excrement.

Some foreign healthcare workers, including several US citizens and at least one Briton, have also become infected while working with patients in west Africa.

The International Monetary Fund said that economic growth in Liberia and Sierra Leone could decline by as much as 3.5 percentage points due to the outbreak, which it said has crippled their mining, agriculture and services sectors.