Prime Minister Rishi Sunak has "no plans" to facilitate the return of the Parthenon Marbles to Athens, his spokesman said Monday, as the British leader prepared to meet his Greek counterpart.

The sculptures, also known as the Elgin Marbles, were taken from the Parthenon temple at the Acropolis in Greece in the early 19th century by British diplomat Thomas Bruce, the earl of Elgin.

Athens maintains the marbles were stolen, which Britain denies, and the issue has been a source of contention between the countries for decades.

Greece's prime minister Kyriakos Mitsotakis said Sunday he would push for their return when he meets Sunak in London this week.

But Sunak's spokesman told reporters that the UK leader has been "robust" in his view that the marbles are a "significant asset" to Britain, which has "safeguarded" the treasures "for generations".

"I think the prime minister's on the record that the Parthenon Sculptures in the British Museum were legally acquired under the laws at the time," he said. 

"They're legally owned by the trustees of the British Museum. We fully support this position -- indeed the British Museum Act prohibits the removal of objects from the museum's collection. 

"We have no plans to change the law," he added, claiming "the world comes to the UK regularly to see the marbles".

In his comments Sunday, Mitsotakis likened the collection being held at the museum to the Mona Lisa painting being cut in half.

Athens had been lobbying London for a deal that would return the sculptures under some kind of loan arrangement, he told the BBC.

In January, the UK government ruled out a permanent return after media reported the British Museum was close to signing a deal to return them on loan. 

Mitsotakis said he would also raise the issue with UK opposition leader Keir Starmer, who is the frontrunner to be Britain's next prime minister after an election expected next year.

The Parthenon temple -- built in the 5th century BCE to honour the goddess Athena -- was partially destroyed during a Venetian bombardment in 1687, then looted.

Its fragments are scattered throughout many renowned museums.

The 2,500-year-old collection has been on display at the London museum since 1817. 

Earlier this year, three marble fragments of that had been held by the Vatican for centuries were returned to Greece.

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