Boris Johnson has rejected suggestions by a former prime minister that there may be an “unforgivable moral failure” in the supply of vaccine doses to cover the needs of poor nations.

Leaders of the major industrialised nations at the G7 summit in Cornwall pledged more than one billion doses of Covid-19 vaccine – 870 million jabs shared directly and the rest through funding to the Covax initiative – to poorer countries.

The Prime Minister said this was made up of “a massive contribution by the United States and other friends”, but one of his predecessors, Labour’s Gordon Brown, said the G7 summit “will go down as a missed opportunity” due to the lack of a plan to deliver 11 billion vaccine doses.

Mr Johnson told a news conference at the end of the G7 summit that “we are going flat out and we are producing vaccines as fast as we can, and distributing them as fast as we can”.

The target to vaccinate the world by the end of next year will be done “very largely thanks to the efforts of the countries who have come here today”, Mr Johnson said.

He said the UK’s contribution to the 1 billion dose pledge is another 100 million vaccines from now to next June.

Earlier Mr Brown said the summit could be seen as an “unforgivable moral failure” due to the gap in vaccinations between rich and poor nations.

He told Sky’s Trevor Phillips On Sunday programme: “When we needed 11 billion vaccines, we’ve only got offered a plan for 1 billion.”

He added: “I think this summit will also go down as an unforgivable moral failure, when the richest countries are sitting around the table with the power to do something about it.

“Now that we’ve discovered the vaccine, we have not delivered the comprehensive plan that will deliver vaccination by the middle of next year.”

Mr Brown continued: “We will have a huge problem of a division between the richest countries that are safe and the poorest countries that are not safe.

“But then the problem will come back to haunt the richest countries because we will have contagion spreading that will hurt even the people who are vaccinated because of mutations and variants.”

The scale of the vaccine pledge was criticised by Oxfam, with the charity’s head of inequality policy Max Lawson condemning the G7 for not backing the waiving of intellectual property rights on the jabs.

“A billion vaccine doses donated would have been a drop in the bucket, but they didn’t even manage that,” he said.

“Sharing vaccines will only get us so far – we need all G7 nations to follow the lead of the US, France and over 100 other nations in backing a waiver on intellectual property.

“By holding vaccine recipes hostage, the virus will continue raging out of control in developing countries and put millions of lives at risk.”

Mr Johnson told reporters: “Already of the 1.5 billion vaccines that have been distributed around the world, I think that people in this country should be very proud that half a billion of them are as a result of the actions taken by the UK Government in doing that deal with the Oxford scientists and AstraZeneca to distribute it at cost.”

He also said that no final decision had been taken on lifting coronavirus restrictions in England on June 21.

He said: “We are continuing to look at the data, no final decision has been taken, and the right time to fill everybody in on what we are going to do with Step 4 with June 21 is tomorrow, as I have said.

“That’s when we will be putting out the whole package of information so that everyone can see it together.”