BBC, London
Boris Johnson is pledging to donate most of the UK's surplus vaccine supply to poorer countries in a speech to a virtual G7 meeting on Friday.
He urged rich countries to back a 100-day target for the developing new vaccines for future emerging diseases.
The UK has ordered more than 400 million doses of various vaccines, so many will be left over once all adults are vaccinated.
But anti-poverty campaigners say the UK is not doing enough.
Decisions on when and how much of the surplus will be distributed will be made later this year, with ministers taking into account the supply chain and whether booster shots are needed in the autumn.
French President Emmanuel Macron has told the Financial Times richer countries should send up to 4 to 5% of their current vaccine supplies to poorer nations.
But Foreign Office minister James Cleverly told BBC Radio 4's Today programme the UK would be "looking at a figure significantly greater than that".
He promised the government would be a "global force for good" in fighting the pandemic and, unlike "some countries", the UK would not use the promise of vaccine supplies to other countries as "short-term diplomatic leverage".
But it was" difficult to say" at this stage when the sharing would happen, Cleverly added.
