Buckingham Palace has insisted that King Charles has a non-political role in the Commonwealth, as questions mount over whether he will apologise for Britain’s role in the transatlantic slave trade.

The King will deliver a speech at the major Commonwealth summit in Antigua and Barbuda on Tuesday, where the issue of slavery is expected to dominate talks.

He is expected to speak about the painful legacy of slavery, but the Palace has confirmed that the King's role is about “inspiring and convening, rather than policy-making”, and his position will have to reflect the British government.

It comes amid growing calls from Caribbean nations for the UK to pay reparations and apologise for its role in selling enslaved people for profit.

The Palace added that the King helps “bring people together from both the public and private sectors across the whole family of 56 nations, encouraging practical collaboration and creating momentum behind ideas that are now moving through Commonwealth channels.

“In that sense, His Majesty's most significant contribution has been helping to connect leaders, institutions and investors – many of whom he knows personally from his many years of international diplomacy - around shared areas of interest and concern, creating the conditions in which ambitious Commonwealth-led initiatives can emerge and succeed.”

The British government has never formally apologised for its role in the transatlantic slave trade, with Andy Burnham thought to be the closest that a prime minister has come to making an apology following his comments last week.

Mr Burnham, who is attending the summit in the Caribbean this week, signalled that he was “open” to a formal apology, but rejected calls for financial compensation.

The prime minister expressed his “sorrow and regret for the pain and suffering of so many millions” and said he was open to a “structured dialogue”.

Writing in on Friday, he said: “We are offering a structured dialogue with those affected by the transatlantic slave trade.

“Listening to calls for a formal apology on behalf of the British state will form an important part of this process, and I am open to them.”

But he added: “I do not think that British people today can be held liable for historical wrongs, however heinous, that happened in a different age under different laws and in which they played no personal part.”

He said he would instead launch a drive to restructure debt of the poorest Commonwealth nations and help them repay debt over a longer period and with better interest rates.

The prime minister of Antigua and Barbuda, Gaston Browne, has said there could be a repeat of “atrocities” in the future if there was no compensation for the UK’s role in the transatlantic slave trade.

He added that the consequences of slavery “have not disappeared with the passage of time”.

But Kemi Badenoch has warned that the UK should not apologise for slavery as it would act as “a lever to wedge open the door to ask for cash”.

Kicking off his nine-day tour on Tuesday, King Charles acknowledged the “great suffering of the past” and confirmed that Commonwealth leaders would discuss the legacy of slavery at the summit.

He told hundreds of schoolchildren and leading politicians at an event celebrating Bahamian youth: “Some of what is best in Bahamian culture today, the most joyful, the most hopeful, the most bright was born out of darkness.

“It is only right that we should acknowledge the great suffering and injustices of the past in these islands and beyond, even as we rejoice in the successes of the present and build new opportunities for the future.

“I know leaders of the governments of affected Commonwealth countries will be discussing these matters in Antigua and Barbuda next week.”