Acropolis now! Diplomatic crisis over Elgin Marbles, according to Downing Street. Rishi Sunak broke off talks with the Greek prime minister during his visit after breaking his promise not to inflame a long-term public dispute

Britain and Greece face a major diplomatic crisis today after Rishi Sunak canceled a meeting with his counterpart amid turmoil over the Elgin Marbles.

No10 last night abruptly called off planned talks with Kyriakos Mitsotakis after he stepped up public calls for the return of the ancient artefacts.

And Downing Street raised tensions again today by accusing the Greek prime minister of breaking a promise by acting presumptuously on the issue.

“You are welcome and have the opportunity to share these views with us privately, as you have done before,” the prime minister’s spokesman said.

“We believe that continued efforts to publicly reopen the long-settled issue of ownership of the Marbles have cast a shadow over an otherwise productive relationship with Greece, and that these discussions are best conducted in private.”

“Those were the guarantees that were given to us before this meeting. Those promises were not kept and you saw the follow-up.”

In an unusually public rebuke, Mr Mitsotakis said he was “annoyed” that the talks had been canceled “hours” before they were scheduled to take place.

He used a BBC interview on Sunday to compare the situation to the “halving” of the Mona Lisa.

The dispute could derail delicate behind-the-scenes negotiations over a loan agreement between the British Museum – which the government says legally owns the marbles – and the Greeks.

Rishi Sunak (left) rejected talks with Greek Prime Minister Kyriakos Mitsotakis (right) over his demand for the return of the Elgin Marbles

Athens has long demanded the return of the Parthenon sculptures, which were removed from Greece in the early 19th century by Lord Elgin, when he was British ambassador to the Ottoman Empire.

Athens has long demanded the return of the Parthenon sculptures, which were removed from Greece in the early 19th century by Lord Elgin, when he was British ambassador to the Ottoman Empire.

Mr Mitsotakis said on Sunday he planned to raise the issue in meetings with Mr Sunak and Sir Keir during his visit to London.

He told the BBC he would “meet both Keir Starmer and of course the prime minister” to discuss the return of sculptures he said were “essentially stolen”.

Mr Mitsotakis said British ownership of the Marbles was a form of cultural vandalism akin to “cutting the Mona Lisa in half”.

Downing Street responded: “We clearly do not agree with that.”

“It was legally acquired at the time and is legally the property of the museum management. We support this position and there are no plans to change the law that governs them.”

The Prime Minister’s spokesman raised eyebrows yesterday when he refused to confirm whether the talks were indeed taking place.

And last night it was confirmed that they were gone. “There’s no point in the prime minister holding the meeting if that’s what it’s about,” a Conservative source said.

A government source said Mitsotakis was offered a meeting with Deputy Prime Minister Oliver Dowden instead, but he declined.

Mr Mitsotakis said in a statement: “I express my anger that the British Prime Minister has canceled our planned meeting just hours before its scheduled date.”

“Greece’s positions on the Parthenon sculpture issue are well known.” I was hoping to have the opportunity to discuss this with my British counterpart. “Those who believe in the correctness and justice of their positions are not afraid to engage in arguments,” he said.

However, the Greek Prime Minister discussed the matter with Sir Keir last night.

A Labor source stressed the issue was not the “core” of the meeting, adding: “They discussed the importance of close cooperation on wider European security, migration and climate action, as well as the important cultural links between both countries. “

Tory sources criticized Sir Keir Starmer after he suggested last week that Labor would not stand in the way of their return to Greece.

“Our position on this is clear: the Elgin Marbles are part of the permanent collection of the British Museum and belong here. “It would be foolish for a British politician to suggest that this should be negotiated.”

The Greek Prime Minister discussed the matter with Sir Keir last night. A Labor source insisted the issue was not the “key point” of the meeting

The chairman of the British Museum, George Osborne, the former chancellor, previously said he was looking at ways to display the Elgin Marbles in Greece, with speculation that this could include a loan deal that would see some of the sculptures sent to Athens be sent, be sent

In a round of interviews this morning, Transport Minister Mark Harper said: “The deputy prime minister offered to meet the Greek prime minister today, but it turned out that was not possible.”

“It is a matter of regret.” This offer has been made.

“But the government has made its position on the Elgin Marbles very clear, which is that they should remain part of the British Museum’s permanent collection.”

Asked on BBC Breakfast if it was a slight against Mr Sunak, Mr Harper said: “I made the case. ‘I can repeat it again and again.’

Labor sources said Sir Keir, whose constituency of Holborn and St Pancras is home to the British Museum, would not ‘stand in the way’ of a loan deal.

A Labor spokesman said: “Strong cultural and historical partnerships between countries are important to ensure that the British Museum and other British cultural institutions can maintain their world-leading status.”

“The next Labor government will consider the case of the British Museum and its chairman in any proposed changes to the Heritage Act as it stands. “We have no current plans to change that.”