“If I were to ‌speak to the king separately from that, I would probably encourage him to return the Koh-i-Noor Diamond,” Mamdani, who is Indian American, said when asked at a ​press conference hours before a ceremony that commemorated victims of ​the deadly September 11, 2001, attacks.

Later in the day, the ⁠king spoke with Mamdani at the ceremony. Buckingham Palace declined to ​comment.

Mamdani’s office did not respond to a request to comment on ​whether Mamdani brought up the issue with the king.

India has repeatedly demanded that Britain return the 105-carat diamond.

Britain’s then colonial governor-general of India arranged for the huge diamond ​to be presented to Queen Victoria in 1850 after the East ​India Company had annexed the region of Punjab in 1849 and taken the diamond ‌from ⁠a deposed Indian leader.

Charles, on Wednesday, commemorated victims of the September 11, 2001, attack on New York City, laying a floral bouquet at the memorial where the World Trade Centre’s twin towers once stood.

India received independence ​from British rule ​in 1947.

The ⁠British colonisation of India and widespread atrocities committed against Indians during that period remain sensitive issues in the country.

India ​has previously said the diamond was a “valued piece of ​art ⁠with strong roots in our nation’s history.”

The diamond’s possession by the British is seen by many Indians as a symbol of colonial atrocities during ⁠British ​rule.

The diamond has been previously owned by India’s ​Mughal emperors, shahs of Iran, emirs of Afghanistan, and Sikh maharajas, according to the Historic ​Royal Palaces charity.