THE PM cancelled a meeting with his Greek counterpart yesterday over the Elgin Marbles — triggering a row.
Kyriakos Mitsotakis had been due to ask Rishi Sunak for their return.
A spokesman said he was “disappointed and extremely surprised” their meeting in London was axed “at the 11th hour”.
Sources claimed Mr Mitsotakis had been left “baffled” and “annoyed”.
The PM has insisted the British Museum is the “right place” for the treasures, removed from Greece by Lord Elgin in the early 19th century.
Mr Mitsotakis compared their loss to cutting the Mona Lisa in half.
Greece, which has long demanded Britain give these treasures up, has insisted a clause about their return be inserted into any agreement.
Labour leader Sir Keir Starmer has said he would not stand in the way of a loan deal.
In 2020, EU chiefs demanded that Britain return the Elgin Marbles to Greece in a new condition for a trade deal.
A senior Downing St source fumed: “It’s just not happening. The Elgin Marbles are going nowhere.”
And a UK Government spokesman insisted: “This is not up for discussion as part of our trade negotiations.”
Ex Culture Minister Ed Vaizey said any attempts to “strong-arm” No 10 would be a “non-starter” as the British Museum owns the marbles.
The row risked souring relations between the two sides a fortnight to the day before talks are set to open.
Greece has repeatedly lobbied for the repatriation of the 2,500-year-old sculptures which were taken from the Parthenon over 200 years ago.