Leaders of the world's most powerful economies have vowed to do all they can to "extinguish" the deadly Ebola outbreak in west Africa.

"G20 members are committed to do what is necessary to ensure the international effort can extinguish the outbreak and address its medium-term economic and humanitarian costs," G20 leaders said in a statement during a summit in Brisbane.

British Prime Minister David Cameron earlier offered Britain's help in co-ordinating the deployment of healthcare professionals from around the world to the three west African states most affected by the outbreak - Liberia, Sierra Leone and Guinea.

Japanese premier Shinzo Abe has already said he is ready to give more money.

He was one of a number of world leaders who Mr Cameron had been lobbying at the G20 summit in Australia to step up their response to the deadly epidemic.

While the UK has pumped in £230m in official funding and taken the lead in operations on the ground in Sierra Leone, some of the other G20 countries - 20 of the world's most industrialised economies, who between them account for 85% of global GDP - have provided little or nothing.

Mr Cameron persuaded Australian Prime Minister Tony Abbott to put Ebola on the agenda for the G20 gathering in Brisbane, and he has been putting intense pressure on countries like Brazil, Mexico and Indonesia for support.

Brazil has so far donated little more than £2m, while Mexico and Indonesia have yet to put in significant amounts.

Other G20 countries regarded as lagging behind in the international response include South Korea and Argentina.

DRC 'Ebola-free'

Meanwhile, the Democratic Republic of Congo has declared itself Ebola-free, after a three-month outbreak of the killer disease claimed at least 49 lives.

The DRC outbreak, which began in August, involved a different strain of Ebola from the one that has claimed more than 5,100 lives in west Africa.

"The end of the epidemic... does not mean we are completely out of danger," said DRC Health Minister Felix Kabange Numbi.

"Like every other nation, the DRC remains threatened by the possible import of the Ebola virus disease raging in west Africa."

The all-clear in the DR Congo came 42 days after the last recorded case of the virus, which has a 21-day incubation period.

The outbreak raging in west Africa stems from the Zaire species -- the deadliest of the five known distinct species -- which caused the world's first known Ebola outbreak in 1976 in what is now known as the DRC.

Until now that outbreak was the deadliest on record, with 280 deaths.

The disease takes its name from the DRC's Ebola River.