Prime Minister Boris Johnson will urge leaders of other wealthy countries to commit to vaccinating the world against Covid-19 by the end of next year.
He will lay out a target for global vaccination at a summit of the G7 group of advanced economies on Friday.
The US, France, Germany, Italy and Japan have all said how many doses they will donate to the global vaccine programme, Covax.
But the UK and Canada are yet to put figures on their planned contributions.
Ahead of the summit, which will take place in Carbis Bay, Cornwall, from 11 to 13 June, Mr Johnson said he will ask his counterparts to “rise to the greatest challenge of the post-war era” by “vaccinating the world by the end of next year”.
“I’m calling on my fellow G7 leaders to join us to end this terrible pandemic and pledge will we never allow the devastation wreaked by coronavirus to happen again,” he said.
Such an achievement would be the “single greatest feat in medical history”, he added.
The summit will be the G7 leaders’ first face-to-face meeting since the start of the pandemic, and US President Joe Biden’s first visit to the UK since taking office.
The US has pledged to donate 80 million doses to poorer countries, while other G7 countries have offered much smaller numbers.
There has been frustration from campaigners that the UK has not specified how many it will pledge, but BBC Global Health Correspondent, Naomi Grimley, says the prime minister will do so at the summit.
As well as dose-sharing, the UK will encourage more discussion about how manufacturing can be stepped up in the coming months.
So far, the UK has only vowed to donate surplus doses to the international Covax scheme, which aims to ensure fair access to vaccines among rich and poor nations
On Friday, Health Secretary Matt Hancock said: “At the moment we don’t have any excess doses, we’re just getting them into arms as quickly as possible.”
More than 40 million people in the UK (76.2% of adults) have had their first dose, according to the government’s coronavirus dashboard. Some 27 million people have had two doses (51.6% of adults) and are fully vaccinated.
In England, the gap between doses was reduced last month from 12 to eight weeks for people over 50 and those with severe underlying health conditions.
The NHS is urging those who have been asked to bring forward their second jab to rebook as soon as possible.
Military personnel have been brought in to help speed up the vaccine programme across the UK in the wake of a recent surge in cases partly driven by the Delta variant, which was first identified in India.
The UK has ordered more than 500 million doses of seven of the most promising vaccines, including the four so far approved for use.
Downing Street said the UK has “led efforts to ensure the world’s poorest and most vulnerable people have access to vaccines”, referring to its funding of the Oxford-AstraZeneca jab.
It said 96% of the 80 million doses administered by Covax have been supplied by AstraZeneca, and that the UK has given £548m to the scheme.