Boris Johnson will pledge to donate the majority of surplus coronavirus vaccines to poorer nations as he tries to rally world leaders to work together on efforts to combat the pandemic.

The Prime Minister will chair a virtual gathering of G7 leaders on Friday, including US President Joe Biden in his first major multilateral meeting, to discuss the response to the crisis.

Mr Johnson will also urge them to back an ambitious target of supporting the development of vaccines for emerging diseases in 100 days in future, a third of the time it took to successfully develop the Pfizer/BioNTech jab.

By harnessing our collective ingenuity, we can ensure we have the vaccines, treatments and tests to be battle-ready for future health threats, as we beat Covid-19 and build back better together

The Prime Minister will use the meeting to confirm that the UK will share the majority of its surplus Covid-19 vaccines with the international Covax initiative to support developing countries.

He will urge the G7, made up of the US, Japan, Canada, Germany, France and Italy along with the UK, to increase funding for Covax.

Decisions on timing and the scale of any surplus will be decided later in the year, although Government sources indicated that well over 50% of excess doses would go to Covax.

It will depend on the reliability of the vaccine supply chain and whether new vaccines are needed for emerging variants or booster shots in the autumn.

Along with the existing jabs, the Prime Minister will call on the leaders to support efforts to slash the time taken to develop and approve new vaccines and treatments, in line with a 100-day ambition set out by the Coalition for Epidemic Preparedness Innovations (Cepi).

Chief scientific adviser Sir Patrick Vallance will work with the World Health Organisation and Cepi, along with industry and scientific experts, to draw up plans to speed up the process.

Mr Johnson said: “Perhaps more than ever, the hopes of the world rest on the shoulders of scientists and over the last year, like countless times before, they have risen to the challenge.

“The development of viable coronavirus vaccines offers the tantalising prospect of a return to normality, but we must not rest on our laurels.

“As leaders of the G7 we must say today: never again.

“By harnessing our collective ingenuity, we can ensure we have the vaccines, treatments and tests to be battle-ready for future health threats, as we beat Covid-19 and build back better together.”

Friday’s video conference is the first meeting of G7 leaders since April 2020 and comes ahead of a summit in Cornwall in June.

Officials believe that will be able to go ahead in person, although it will be scaled-back compared to previous G7 meetings as a result of coronavirus.

Huge efforts have been devoted to the arrangements, with officials working with Public Health England to ensure it will be safe.

A rigorous testing regime and a system of “bubbles” are likely to be used to prevent the spread of coronavirus.

As well as the regular G7 members, the Prime Minister has invited the leaders of India, South Korea and Australia to attend as part of his agenda of creating a “D10” of leading democracies.

The Prime Minister has already called for an international treaty on pandemic preparedness.

Mr Johnson wants to ensure the lack of international co-operation going into the pandemic should not be mirrored on the way out of it.

Other issues likely to be on the agenda during the UK’s presidency of the G7 include climate change and the economic recovery from coronavirus.

The One Campaign, a global movement working to end extreme poverty and preventable disease by 2030, said Mr Johnson’s commitment does not go far enough.

Romilly Greenhill, UK director of The One Campaign, said: “The Government needs to be going much harder and faster.

“Sharing surplus doses through Covax is the right thing to do, but there is a real risk of double standards if we talk a good game on global vaccines access but continue to stockpile more doses than we need.

“The virus won’t wait on us to be ready before it mutates, so we need to get these vaccines around the world as quickly as possible.”