King Charles has given his support to research that will examine the British monarchy's links to slavery, Buckingham Palace said on Thursday, after a newspaper report said a document showed a historical connection with a transatlantic slave trader.

The Guardian said an archive document discovered by historian Brooke Newman showed that in 1689 King William III had been given 1,000 pounds of shares in the Royal African Company (RAC) which was involved in the transportation of thousands of slaves from Africa to the Americas.

The recently discovered document was signed by Edward Colston, a slave trade magnate whose history became widely known after protesters pulled down a statue to him in Bristol, southwest England, and threw it in the harbour during 2020 Black Lives Matter protests.

"This is an issue that His Majesty takes profoundly seriously," Buckingham Palace said in a statement.

The issue of the British Empire's slavery links and calls for possible reparations from the monarchy has been growing in the Caribbean where King Charles remains head of state of a number of countries including Jamaica and the Bahamas.

Buckingham Palace said the royal household would help to support an independent research project looking into any links between the monarchy and slavery during the late seventeenth and eighteenth-centuries, by allowing access to the Royal Collection and the Royal Archives.

The Palace highlighted a speech King Charles made to Commonwealth leaders last June, when he said: "I cannot describe the depths of my personal sorrow at the suffering of so many as I continue to deepen my own understanding of slavery's enduring impact."

That process had continued with "vigour and determination" since King Charles succeeded his mother on the throne last September, it said.

There were a protests and calls for an apology for slavery when King Charles's eldest and now heir Prince William went on tour with his wife to the Caribbean in March last year.

"Given the complexities of the issues it is important to explore them as thoroughly as possible," the Palace statement said. "It is expected that the research will conclude in September 2026."