Rishi Sunak opened the door to a “devastating line of attack” from Labour by snubbing his Greek counterpart this week, according to the British Museum’s chair George Osborne, who said the row had encouraged the institution to press ahead with talks over loaning the Parthenon marbles to Athens. Osborne said: “That is, I think, something worth exploring. And we can go on doing it whether or not Rishi Sunak meets the Greek prime minister or not. In fact, if anything, things have been rather clarified by this week. We obviously know we’re not going to get any particular support from the Conservative government.” No 10 has said that the former Tory chancellor – as a “private individual” – could continue with any talks he wanted but warned that it saw moves to remove the sculptures from the UK as a “slippery slope” that could lead to the return of other contested antiquities. Osborne said on his podcast, Political Currency, that he had been trying to find out what lay behind Sunak’s decision to cancel the meeting with the Greek PM, Kyriakos Mitsotakis. He said he had examined theories including that it was a “dead cat” strategy to deflect from the government’s woes around immigration policy and an attempt to impress “red wall” voters. “Then you ask the question, is it just petulance? Is it just having a bit of a hissy fit? And, I think if that’s the reason it’s not because Mitsotakis was going to raise the Elgin marbles. It’s because he had met [Labour leader] Keir Starmer the day before,” said Osborne. “And I think in No 10, I remember being there in 1996 and 1997, you can sort of feel the power start to drain from the building when you’re getting close to an election which people think you’re not going to win. And I thought, you know, what Rishi Sunak did was open the door – and this was definitely not what he should have done – to a pretty devastating line of attack from Keir Starmer at prime minister’s questions this week.” Osborne added that the British Museum was not attempting to change the law – a reference to the British Museum Act 1963, which prohibits the museum from permanently removing objects from its collection – but confirmed he had been holding talks with the Greek government about a potential deal. It would involve the sculptures being in London and Athens at different times and Britain receiving “Greek treasures” in return. Sunak attempted to draw a line under the diplomatic row on Thursday – a day after accusing Mitsotakis of “grandstanding” over the issue – when he said on a visit he was “focusing on the things that really matter to people”. Sources in the British government have cautiously suggested that there may be a “brush-by” involving Sunak and Mitsotakis at the Cop28 summit in Dubai on Friday. However, there has been fresh criticism of Sunak by the leader of the Greek Orthodox archdiocese of America, Archbishop Elpidophoros, who tweeted that he had “insulted Greeks worldwide”.