WASHINGTON (AFP) - US President Joe Biden said Tuesday (May 11) that almost half the world's leaders have contacted him, asking for US help in obtaining Covid-19 vaccines.

"Every country in the world is now looking at us to provide for their lack of capacity to produce and/or have vaccines," Biden said in a virtual meeting with US state governors.

"I literally have, virtually 40 per cent of the world leaders calling and asking, can we help them," Biden said. "We're going to try."

The US leader did not say which countries he was referring to. However, there is a growing international clamour for sharing the enormous US surplus in vaccines, including in hard-hit India.

Biden pledged last month to distribute 60 million AstraZeneca doses, with India expected to be a recipient. Earlier, the White House said it was loaning four million AstraZeneca doses to neighbouring Mexico and Canada.

However, Washington has come under growing pressure to release more vaccines, given a surplus expected to amount to hundreds of millions of doses.

Biden repeated his position that he is prioritising getting Americans inoculated but said "we are going to be working with other countries, because there are going to be a lot of variants."

"I think we can produce a whole hell of a lot more vaccines that we can make available," he said.