Burnham asks slavery-affected countries to help shape expected formal apology

No 10 said Burnham would use the summit, which begins on Tuesday, to launch a "structured dialogue" into what form an apology might take, arguing that the input of affected countries is indispensable in crafting an enduring message. His official spokesperson said: "We think it's right that a formal apology is discussed properly with the countries and communities most affected, rather than simply deciding unilaterally what form it should take. An apology of this significance should be informed by the people and countries most affected, as they have asked for."

The spokesperson said Burnham, like his predecessors, had expressed sorrow and regret for the pain and suffering caused by the transatlantic slave trade, but that this was “distinct from a formal apology”. The Foreign Office would lead talks on the form an apology might take, No 10 said, and Burnham is due to join King Charles at the formal opening of the meeting.

Reparations have dominated the build-up to the gathering of representatives from 56 Commonwealth countries. Before the previous summit, held on the Pacific island of Samoa two years ago, Sir Keir Starmer said reparations were not on the agenda while other leaders insisted they should be. Burnham wrote in the Guardian that Britain had damaged the Commonwealth by avoiding the subject: "By sticking our heads in the sand, we have damaged the ability of the Commonwealth to function." He said: "Britain is bringing a new approach to this meeting as we look to reshape a new era for the Commonwealth, as well as being open to discussions about the past."

Downing Street has ruled out paying reparations after any apology. Burnham is expected to set out plans at the summit for what Downing Street calls a “debt reset”, aimed at supporting Commonwealth countries facing the growing costs of paying interest on their debts.

In a social media video, the foreign secretary, Ed Miliband, said a formal apology was something "the British government are open to", and described it as a "significant step". But he said the government did not believe financial reparations were the right answer to transatlantic slavery, and did not think the right response was to ask British taxpayers today to make financial payments for historic acts. The BBC reported that the UK is likely to formally apologise for the slave trade for the first time next year, when it holds the rotating G20 presidency.

The Conservative leader, Kemi Badenoch, urged the prime minister not to issue an apology, saying it would give countries a reason to ask the UK for reparations. She said: "I don't think we should be giving any money to compensate people for the slave trade, and I don't think that Andy Burnham needs to be apologising because it is a lever to wedge open the door to ask for cash."

British officials are hopeful that the approach will create space in the next two days for a wider conversation. One Foreign Office official said other Commonwealth countries "are responding positively to our offer of a structured dialogue", adding: "By not shying away from difficult discussions about our past, we are building trust with our allies to focus on the big issues of the future." UK officials said the move could also help talks on separate issues such as trade and climate.

No 10 said the UK would lead two new task forces, one focused on critical mineral assets and vulnerabilities in supply chains across the group, the other aimed at boosting trade and investment. Both will be set up by the end of the year and report back at the next leaders' summit.

No 10 denied that Burnham's comments had potentially embarrassed the King, who is already in Antigua and Barbuda. Burnham's spokesperson said Buckingham Palace “was made aware in a timely manner”.