When King Charles III opened a Commonwealth of Nations (Commonwealth of Nations) leaders' summit in the Caribbean, he described the transatlantic slave trade as a "shameful chapter in history" that he found "extremely sad."
He said the slave trade "casts a shadow" over the union of nations "to this day".
Ahead of the Commonwealth Heads of Government Meeting (CHOGM) in Antigua and Barbuda, there were calls for the UK to formally apologize for its historical role in the slave trade, but the King did not make an apology in his speech.
British Prime Minister Andy Burnham, who also attended the summit, said he was willing to consider a formal apology from the UK but ruled out providing monetary compensation.
While he did not apologize directly, the King did express a degree of apology and acknowledged that he had personally learned more about the legacy of the slave trade.
"The transatlantic slave trade still casts a shadow over these islands and other members of the Commonwealth today," he said.
"As I have said before, this shameful chapter in history fills me with fear in my heart and the deepest personal sorrow in my soul."
He told the summit: "The deeper I understand these issues through listening, learning and observing, the more committed I am to finding ways for us to work together in modern partnerships to correct the mistakes of the past with future-oriented actions."
King Charles continued: "History is not chosen or changed by us. It is passed down in complex ways by ancestors we have never met."
"We inherit both their achievements and their failures; their good deeds and their mistakes."
The King's speech also mentioned the "brutal conflicts" the world is facing, the "catastrophic reality" of climate change, and the rapid development of technology.
The Commonwealth Heads of Government Meeting is held every two years in different countries or regions of the Commonwealth, bringing together leaders of the 56 member states. The Commonwealth is a voluntary organization whose members are primarily former territories of the British Empire.
The official theme of this year's biennial conference is "Accelerating Partnership and Investment for a Prosperous Commonwealth."
Bayend said on Tuesday (November 3) that despite rejecting the compensation request, his government is taking a new approach with the goal of "reviving the Commonwealth."
"I've made it very clear that we do not support reparations," he said.
"But this does not mean that we do not support the development of Commonwealth countries, nor does it mean that we do not assist them in dealing with debt problems and providing green financing."
"That's what every government has done, and I think as a Commonwealth we should continue to do that."
The King and Queen are visiting the Caribbean, a trip that has reignited difficult debates about Britain's colonial legacy there.
The King spoke of "the suffering of the past" in a speech during the first leg of his visit to the Bahamas.
While in Guyana, he visited the site of a slave revolt in which hundreds of enslaved people died.
Foreign Minister Wen Li-bin: The history of the slave trade can no longer be "turned a blind eye"
BBC political editor Chris Mason reports from Antigua
Foreign Secretary Ed Miliband insisted the government's willingness to consider a formal apology for Britain's role in the transatlantic slave trade would not lead to higher costs for the British taxpayer.
The Prime Minister said the UK would not compensate affected countries but declined to say whether his new approach might involve using more taxpayers' money.
Wen Libin said on the BBC's "Newscast" podcast that successive British governments have always adopted a "sweep under the carpet" (turn a blind eye) attitude towards the pain and consequences of slavery. He referred to former Prime Minister Sir Tony Blair's remarks on this issue nearly 20 years ago, calling it "an apology but not an apology".
In 2007, Sir Tony Blair said that Britain's involvement in the slave trade was "deeply sad and regrettable".
Wen Libin said: "Barley adopted an approach that was not an apology to a certain extent. He expressed grief and then said he was sorry, but No. 10 Downing Street later played down these remarks."
"We think it's the right thing to do to address this issue, rather than trying to pretend it doesn't exist," Wen said.
Buckingham Palace: The King of England does not play a decision-making role in apologizing for the history of slavery
BBC royal correspondent Sean Coughlan, BBC correspondent Freya Scott-Turner
Buckingham Palace said the King's role as head of the Commonwealth is "to inspire and convene, not to set policy." The statement distanced him from the controversy over whether Britain should apologize and make reparations for its role in the Atlantic slave trade.
The Buckingham Palace statement clarifying that the King has no political role in the Commonwealth comes as Commonwealth leaders gather for a summit in Antigua and Barbuda.
