Prime Minister Boris Johnson is to urge leaders of other wealthy countries to commit to vaccinating the world against Covid-19 by the end of 2022.
He will lay out a global target at the G7 summit which gets underway on Friday.
The US, France, Germany, Italy and Japan have all declared how many doses they will donate to the global vaccine-sharing programme, Covax – but Canada and the UK have yet to release their planned contributions.
Ahead of the G7 gathering in Cornwall this week, Mr Johnson said he would ask his counterparts to “rise to the greatest challenge of the post-war era” by “vaccinating the world by the end of next year”.
“Such an achievement” he said, “would be the single greatest feat in medical history.”
The US has pledged to donate 80million vaccine doses to poorer countries, while other G7 countries have offered significantly lower quantities.