New York City’s mayor says he would urge the King to return a long-disputed crown jewel to India if they spoke privately.

Zohran Mamdani was among dignitaries who met the King and Queen at a ceremony in the city on Wednesday commemorating victims of the September 11, 2001 attack on the city by al Qaeda.

As part of their four-day state visit to the United States, the royal couple visited the National 9/11 Memorial in lower Manhattan, where Charles laid flowers.

Mr Mamdani told reporters before the event: “If I were to speak to the king separately from that, I’d probably encourage him to return the Koh-i-noor diamond.”

The Koh-i-Noor diamond, which is one of the largest-cut diamonds in the world, was mined in India and dates back to at least the 17th century. The Indian government has demanded its return from Britain several times since independence in 1947.

Once owned by Queen Victoria, it is part of the British Crown Jewels and displayed in the Tower of London. It is said to be priceless.

In 1849, with India under colonial rule, the British East India Company forced the 10-year-old son of the Indian royal family to give up ownership of the Koh-i-Noor. India’s most recent request for it was in 2016.

Twice in three days after being asked about any message he would like to send to the royal couple at Ground Zero, Mr Mamdani omitted them from his initial answer.

“I’ll be attending a wreath laying alongside other elected officials including Gov Hochul, Gov Sherrill, and the focus of that wreath-laying is to honour the more than 3,000 New Yorkers who were killed in the horrific terror attacks of September 11,” he said. “And that is really what I’m looking to do at that event.”

A spokesperson for the royal family declined to respond to Mr Mamdani’s remarks, according to Politico. The Independent has asked Buckingham Palace to comment.

Earlier, Buckingham Palace responded after President Donald Trump claimed that King Charles agreed with him that Iran should not be allowed to obtain a nuclear weapon.

Members of the royal family are constitutionally required to remain strictly neutral on politics. However, on Tuesday night, Trump said the US would never allow Iran to obtain a nuclear weapon – and surprised guests by suggesting the King shared that view.

“Charles agrees with me even more than I do,” Trump said. In his ‌own comments later, the King did not speak about Iran or the Iran war.

A Palace spokesperson responded: “The King is naturally mindful of his government's long-standing and well-known position on the prevention of nuclear proliferation.”