Aid organisations are questioning the federal government's claim it does not have the capacity to repatriate Australians from West Africa if they become infected with Ebola.

Foreign Minister Julie Bishop on Thursday announced Australia would immediately boost its financial contribution to fighting the worst ever outbreak of the deadly disease by another $10 million, taking the total commitment to $18 million.

The latest offering follows an urgent call from the United Nations for more help, with the worldwide death toll from Ebola jumping to 3338 and 7178 infected since the beginning of the year, according to the World Health Organisation.

Ms Bishop said Australia had limited capacity to provide consular assistance in the five West African countries affected, and insisted the government does not have the capacity to evacuate Australians who contract Ebola.

"The government has assessed that, at this stage, financial contributions are the best and most efficient way Australia can make a rapid contribution to the global response," Ms Bishop said in a statement on Thursday.

But the aid organisations, Médecins Sans Frontières and Save the Children, while welcoming the additional aid money, both insist Australia could put boots on the ground.

MSF spokeswoman Dr Myrto Schaefer says the government is confusing the difference between repatriation and evacuation, adding that there are already systems in place, co-ordinated by the WHO, to ensure the safety of aid workers.

"It's not about getting people, in this case Australian citizens, who are infected with Ebola back to Australia," Dr Schaefer told AAP.

"Up until now there has not been one single case of an expatriate who has been infected that has not been successfully evacuated to a treatment centre in Europe," she added.

"The WHO is co-ordinating (evacuations). There is a means to medically evacuate."

Ms Bishop said the government had been discussing with other countries located geographically much closer to West Africa as to whether or not Australian health workers can be evacuated to their countries.

"At this time we have no guarantees from any other country," she said.

Save the Children on Thursday also challenged the Australian government's refusal to send skilled staff like doctors, engineers and logisticians, while other world leaders deployed troops and medical experts in their hundreds.

The US has committed up to 3000 troops while the UK will spend $185 million on its mission, including supporting 700 Ebola treatment beds across Sierra Leone.

"Make no mistake, this crisis is at tipping point. We need to act urgently and decisively," Save the Children acting chief Mat Tinkler said.

The UN is seeking $US50 million ($A54 million) from donors to meet immediate needs over the next four weeks, including for logistics to deliver equipment, materials and supplies to Ebola response operations.