King Charles has described the transatlantic slave trade as a "shameful chapter of history" that filled him with "profound sorrow" as he opened a summit of Commonwealth leaders in the Caribbean.
He said the trade in enslaved persons "still casts a shadow" over the association of nations.
There have been calls from some for the UK to make a formal apology for its historic role in the slave trade ahead of the Commonwealth Heads of Government Meeting (Chogm) in Antigua and Barbuda, but there was not one in the King's address.
Prime Minister Andy Burnham, also at the summit, has said that he is open to Britain issuing a formal apology but has ruled out financial reparations.
While there was no direct apology, the King did offer some contrition - and there was also an acknowledgement that he had personally learnt more about the legacy of the slave trade.
He said: "The transatlantic trade in enslaved persons still casts a shadow over these islands and other members of our Commonwealth.
"As I have said before, that shameful chapter of history is one that fills my heart with horror and my soul with the most profound personal sorrow."
He told the summit: "The more I have furthered my own understanding of the issues, through listening, learning and looking, the more committed I have become to finding ways for us to work in modern partnership to address the wrongs of the past with action for the future."
King Charles continued: "History is not ours to choose or to change. It is bequeathed to us in complex synthesis by forebears we can never know.
"Our inheritance includes both their achievements and their failures – the good they did as well as the wrongs."
The King's address also referenced the "brutal conflicts" the world is facing, the "catastrophic reality" of climate and rapid technological development.
The Chogm meeting gathers leaders from 56 states every two years in a different part of the Commonwealth, a voluntary grouping made up primarily of former territories of the British Empire.
The biennial meeting's official theme this year is Accelerating Partnerships and Investment for a Prosperous Commonwealth.
Speaking on Tuesday, Burnham said his government was bringing a new approach, aiming to "revitalise the Commonwealth", despite turning down demands for reparations.
"I've been very clear that we do not support reparations," he said.
"But it's not the case that we don't support countries in the Commonwealth around development, and helping them with debt issues that they've got, green finance.
"That's what we've done under all governments and in my view we should continue to do as part of being a Commonwealth."
The King and Queen are on a tour of the Caribbean which has reignited difficult debates over the UK's colonial legacy in the region.
On his first stop in the Bahamas, the King delivered a speech in which he spoke of the "suffering of the past".
In Guyana, he visited the site of a Slave Rebellion, where hundreds of enslaved people were killed.
Source: BBC
– Agencies
