The British Museum is facing legal action from one of the UK’s leading heritage preservation organisations over its refusal to allow the 3D scanning of a piece in its Parthenon marbles collection. The Institute for Digital Archaeology (IDA) said it would serve an injunction against the museum imminently, raising the stakes in the dispute between the two. “We will be filing a complaint by the end of the week requesting the court to order the British Museum to grant our request,” Roger Michel, the IDA’s executive director, told the Guardian. “We want them to treat our application in exactly the same fashion that they would treat similar requests. Their refusal has been capricious and arbitrary.” The Oxford-based institute had hoped, with the museum’s blessing, to reproduce one of the high relief metopes from the Acropolis temple’s south facade as “proof of concept.” In 2016 it reconstructed Syria’s Palymyra arch of triumph out of Egyptian marble based on photographs following the monument’s destruction by Islamic State. Advocates believe 3D imaging could be employed to not only create replicas of the classical treasures but help resolve the longstanding row between Athens and London over patrimony of the Parthenon marbles. Scans would allow a robot sculptor to reproduce the artworks with sub-millimetre accuracy using the same Pentelic marble from which the originals were chiselled, according to the IDA, a supporter of the marbles’ repatriation to Greece. “Our aim is to give people a chance to see just how extraordinary a copy can be,” said Michel, a Harvard-trained American lawyer who founded the institute, which has collaborated with Unesco, and describes its mission as preserving and restoring ancient artefacts at a time when irreplaceable objects are under “obvious threat” of being lost forever. “Copies [of the Parthenon sculptures] in the past have been low-quality plaster casts. This will be orders of magnitude better. It will help people see and feel the potential of this technology in ways mere words can’t describe.” Peter Higgs, the museum’s acting keeper of Greek and Roman antiquities, conceded that digital scanning of the 5th-century BC sculptures could “unlock new discoveries”, but the IDA was told by email that its request could not be facilitated, five weeks after it was made. Michel and his team visited the British Museum last week despite the ban, deploying what he described as an “iPad on steroids” to scan the piece from the floor of the Duveen gallery. The organisation argued it was within its rights to do so as it said the British Museum’s own guidelines “plainly authorise” the use of 3D software to capture images of the antiquities in the gallery. The news, however, prompted anger from the museum. “The British Museum was deeply concerned to hear suggestions that unauthorised scanning took place in our galleries. Any such activity would be a breach of our visitor regulations,” a statement said. “We regularly receive requests to scan the collection from a wide range of private organisations … and it is not possible to routinely accommodate all of these.” Michel responded in an email seen by the Guardian: “The guidelines plainly authorise exactly what we did, referencing as they do ‘3D software’, ‘3D imaging’, ‘scans’, ‘scanned data’, ‘cameras’, and ‘phone cameras’. “Far from expressing any doubts about the propriety of our activities, your security staff were eager to learn more about the process and were most helpful and encouraging. I’m sure it was all captured by your CCTV. In view of all these facts, your characterisation of our activities represents a gross distortion of the truth; I hope you will correct your obvious misstatements forthwith.” In a later statement to the Guardian after the IDA’s threat of legal action, a museum spokesperson restated it was not possible to routinely accommodate all requests from “private organisations – such as the IDA – alongside academics and institutions who wish to study the collection”, emphasising how important it was that “any request is properly supported so that, to the best of our ability, we can ensure the highest levels of quality and academic rigour”. It added that it already used cutting-edge technologies to explore and share its collection and had facilitated visits from the Acropolis Museum in 2013 and 2017 for 3D scanning. The scanning furore has dismayed officials in Greece at time of a shift in attitudes among some of the world’s leading museums to the repatriation of contested artefacts. “How in the world can they deny such a request when the museum boasts about its educational and enlightening role?” said Elena Korka, the honorary director general of antiquities and cultural heritage at the culture ministry in Greece. “What is so worrying about a scan? To me it seems totally absurd and in total contradiction to the museum’s self-professed role.” The antiquities, regarded as the high point of classical art, have been in the British Museum’s possession since 1816 after their removal from the Parthenon at the behest of Lord Elgin, the British ambassador to the Ottoman empire, which then controlled what is now modern Greece. Successive Greek governments have argued that the antiquities were illegally hacked from the temple at a time when it was a subject nation without voice or sovereignty. The British Museum says they were legally acquired. Emboldened by surveys showing a majority of Britons supporting their return, the Greek prime minister, Kyriakos Mitsotakis, has reinvigorated the campaign to reunite the artworks with the rest of the monumental frieze, displayed in the Acropolis Museum within view of the site the sculptures once adorned. In an unprecedented step Mitsotakis placed the issue at the centre of talks with Boris Johnson in Downing Street last November, reminding the UK prime minister of his love for Greece. As a classics student at Oxford, Johnson had been a supporter of the statuary being sent back to Athens. Michel said that while his team had managed to complete most of the digital imaging with the help of the iPad program, there were still parts of the metope that could be better scanned with a ladder if a permit was eventually granted. “There is a little bit at the top that we would like to get a better look at,” he said. In their present form, “battered and whitewashed” in the Duveen gallery, the IDA director argues, the sculptures bear no relation to the their true aesthetic in antiquity – something, he believes, the creation of replicas could also help resolve. “Reconstruction could restore the coloured surfaces of the originals – including a range of skin tones,” he said. “In short, reconstructions could help the British Museum do all the things it claims it wants to do so much better.”