Senior Greek officials have been in “preliminary” talks with the British Museum in what could amount to a tectonic shift in resolving the world’s longest-running cultural dispute: the repatriation of the 5th-century BC Parthenon marbles to Athens. Revelations about the negotiations were first reported on Saturday by Ta Nea, which said that officials including the Greek prime minister, Kyriakos Mitsotakis, had met George Osborne, the chair of the British Museum, in a five-star London hotel as recently as Monday. Insiders in Athens described the report, which gave a blow-by-blow account of where the talks had been conducted, as “not only credible but very exciting”. “It is true there is a dialogue between the Greek government and the British Museum,” the country’s minister of state Giorgos Gerapetritis told the Guardian. “Right now, they are preliminary talks and, yes, I have met the British Museum’s chair, George Osborne” [to discuss the issue]. The news came five days after Mitsotakis told an audience at the London School of Economics that he “sensed” headway was being made on the issue and that a “win-win solution” was possible. “We have seen progress,” said the Greek leader, who has made reunification of the classical statuary with the carvings that have remained in Athens a cultural priority. “I do sense a momentum.” The row over the marbles – removed in contentious circumstances by Lord Elgin, who was ambassador at the time to the Ottoman empire of which present-day Greece was then a part – has raged for more than 200 years. The British Museum acquired the antiquities, which include 75 metres of the Parthenon’s original 160-metre-long frieze, in 1816 when, bankrupt, despondent and racked by syphilis, the diplomat was forced to part with them. Elgin, who had initially hoped to adorn his Scottish estate with the treasures, maintained he had been granted a “firman” by Ottoman authorities that permitted his agents in Athens to dismantle the pieces. It has since come to light that much of the statuary was violently detached, with slabs now in the British Museum’s possession hacked from the monument with the use of saws. Ta Nea reported that the first of several behind-the-scenes meetings had taken place in London between Osborne and Mitsotakis in 2021 when the Greek premier made the marbles the centrepiece of Downing Street talks with his then counterpart Boris Johnson. The former chancellor had then followed up with further discussions, meeting Gerapetritis and the Greek foreign minister Nikos Dendias in London. “At least two of those meetings were held at the Greek ambassador’s residence in Mayfair. Another one was held as recently as this week at a hotel in Knightsbridge,” wrote the paper’s London correspondent, Yannis Andritsopoulos. “The discussions have been kept out of the public eye. The chair of London’s largest museum first visited the [Greek] ambassador’s residence, at 51 Upper Brook Street, in mid-November 2021, to hold ‘exploratory talks’ with Mitsotakis about the fate of the 2,500-year-old sculptures.” Negotiations, it said, further evolved this week when Osborne visited the Berkeley hotel in Knightsbridge to meet the Greek premier “a year after their first secret encounter”. The dispute over ownership of the sculptures has descended into acrimony, with the Greek culture minister accusing Elgin of committing a “blatant act of serial theft”. As the rhetoric has intensified, campaigners, backed by growing support among Britons for their return, have piled the pressure on London’s premier cultural institution to alter its stance. “Clever politicians listen to their people,” said Nikos Stampolidis, the Greek academic who heads the Acropolis Museum at the foot of the Periclean site. “If there were a solution, Britain could be the protagonists of an ethical empire because this transcends our countries. If the marbles were reunited here in Athens, within view of the greatest symbol of democracy, it would be a great act for humanity.” Gerapetritis conceded that the talks were aimed as much at “establishing principles” [of discussion] as ameliorating the increasingly toxic atmosphere that had arisen on the issue. Both sides, he said, were aware of their “red lines” and a deal was far from close. “Although there is a common understanding, a lot of details have yet to be worked out,” added the minister, who described Mitsotakis as giving him a mandate to pursue further talks. Asked about his face-to-face talks with Osborne, he insisted: “The discussions are not very specific. Rather, we are trying to establish a good channel of dialogue.” In August, the British Museum’s deputy director, Jonathan Williams, announced that the institution was eager to “change the temperature of the debate” after Unesco ruled it imperative that the affair was discussed at an inter-government level. “There is space for a really dynamic and positive conversation with which new ways of working together can be found,” Williams told the Sunday Times. A statement issued by the British Museum said the talks were part of efforts to create “a new Parthenon partnership with Greece”. “We’ll talk to anyone, including the Greek government, about how to take that forward. We operate within the law and we’re not going to dismantle our great collection as it tells a unique story of our common humanity. But we are seeking new positive, long-term partnerships with countries and communities around the world, and that of course includes Greece.” In the past Mitsotakis’s centre-right government has proposed giving the UK a rotating exhibition of antiquities never before shown outside Greece in return for the Parthenon sculptures. “There are a lot of red lines: the 1963 deaccession act for the British Museum, acknowledgment of British ownership [of the marbles] for us,” said the politician, explaining that Athens would never accept repatriation of the masterpieces as a loan. “There is still a long way to go but we will go on with our discussions. It’s very good that we are now trying to establish a much broader cooperation with the British Museum, one that not only involves classical antiquities but Byzantine treasures that we would be willing to send.”