US President Joe Biden's administration will provide 500 million doses of the Pfizer Covid-19 vaccine to about 100 countries over the next two years, APA reports citing BBC.
About 200 million doses will be distributed this year, with the remainder delivered in 2022.
The US has been under pressure to raise vaccination rates in poor countries.
The move comes as Mr Biden landed in the UK at the start of his first foreign trip as US president.
The White House is yet to officially comment on the plan to roll out 500 million doses worldwide.
But when asked if the US government had a vaccination strategy for the world, Mr Biden said: "I have one, and I'll be announcing it," before boarding Air Force One.