WASHINGTON (AFP) - US President Barack Obama on Wednesday urged Western leaders to do more to stem the global Ebola outbreak, the White House said, as fears mounted worldwide that the virus could spread even more quickly.

Obama urged the leaders of Britain, France, Germany and Italy in a videoconference call to "make a more significant" commitment to global efforts to stop the epidemic, which has already claimed nearly 4,500 lives, White House spokesman Josh Earnest told reporters.

One day before his call with British Prime Minister David Cameron, French President Francois Hollande, German Chancellor Angela Merkel and Italian Prime Minister Matteo Renzi, Obama had expressed frustration with the pace of the international fight against Ebola.

"The world as a whole is not doing enough. There are a number of countries that have capacity that have not yet stepped up," the US leader said on Tuesday.

"All of us are going to have to do more." Obama also spoke with Japanese Prime Minister Shinzo Abe on Tuesday night about the health crisis, thanking him for Tokyo's "important contributions," the White House said.

The US leader urged Abe to "consider additional commitments," it said.