The lack of vaccines in poorer countries is to blame for the development of new coronavirus variants, Gordon Brown has said.

The former prime minister said it is “no surprise” that new variant Omicron was discovered in South Africa earlier this week, and added that new variants are developing because richer countries are “hoarding” vaccines.

His comments came after the UK placed six countries – South Africa, Botswana, Lesotho, Eswatini, Zimbabwe and Namibia – on the red travel list following the discovery of the new variant.

People returning to the UK from those countries will have to quarantine.

Mr Brown said health leaders had given the Government “repeated warnings” that new variants could develop due to a lack of vaccines for poorer countries.

Writing for the Guardian, Mr Brown said: “In the absence of mass vaccination, Covid is not only spreading uninhibited among unprotected people but is mutating, with new variants emerging out of the poorest countries and now threatening to unleash themselves on even fully vaccinated people in the richest countries in the world.”

Fewer than 6% of people in Africa have been fully immunised against Covid-19 and millions of health workers and vulnerable populations have yet to receive a single dose.

Those conditions can speed up the spread of the virus, offering more opportunities for it to evolve into a dangerous variant.

Mr Brown wrote: “The figure exceeds 60% in both high-income countries and upper-middle-income countries. Every day, for every vaccine delivered as first vaccine in the poorest countries, six times as many doses are being administered as third and booster vaccines in the richest parts of the world.”

Speaking to BBC Newsnight, Mr Brown said the UK’s failure to deliver 100 million vaccines, of which it has so far donated 11%, is “probably the biggest international public policy failure of our times”.

He added the decision will “come back to haunt our own country”, and said: “The problem is there are enough vaccines to go around.

“We will have 12 billion vaccines by the end of the year which is enough to vaccinate the whole world. They are being unequally distributed.

“We have set aside vaccines for boosters and young people and there are still spare vaccines for other countries.

“We are depriving people the chance to survive the virus by denying the chance in so many countries to get the vaccines.”

His thoughts were echoed by Dr Osman Dar, project director at One Health Project, who said: “The emergence of a new Covid-19 variant with all its myriad mutations is not unexpected.

“What it highlights are the continuing and fundamental risks to everyone associated with not seriously addressing the inequalities still at play globally in the fight against disease and poor health.”

He added that the travel ban has “economically penalised, socially ostracised and socio-politically stigmatised” the countries on the red list even though they did the “right thing through their timely reporting and sharing of the variant’s genetic data”.

Dr Dar added: “What’s necessary, to limit the negative socio-economic impacts of these restrictive measures on trade and travel, is to have a sufficiently resourced global regime in place.

“This should support countries reporting new variants through the significant financial and social hardships that then ensue – a disaster or pandemic fund specifically engineered around the impacts of trade and travel restrictions.”