Greek Prime Minister Alexis Tsipras is trying to revive the case that the UK should return the 2,500-year-old marbles from the British Museum that were taken from the Acropolis in the 19th century. Known as the Elgin Marbles for the British diplomat who removed them, the stones once comprised roughly half of a 500-foot frieze on the Parthenon.

Travelers vote using an interactive touchscreen that displays pictures of the Parthenon and its marble statues at the Athens International Airport in 2014. Photo: Angelos Tzortzinis /AFP/Getty Images.

The Elgin Marbles have been the subject of an intense repatriation debate over the years. Greece has repeatedly asked for their return to no avail, but Tsipras could be hoping to capitalize on a wave of recent high-profile repatriations, including property returned from the US to Lebanon and Greece.

Tsipras’s office did not immediately respond to a request for comment.

Greece has stepped up its campaign for the marbles since 2009, when it opened a new museum at the foot of the Acropolis hill. In 2014, a previous Greek government hired a legal team including human rights lawyer Amal Clooney to advise it on the issue, Reuters has reported. This latest request coincided with Tsipras’s first official visit to London since he was elected in prime minister 2015, according to Reuters. He raised the issue during a meeting with British Prime Minister Theresa May and told reporters: “The Marbles belong to the world cultural heritage but their natural place is the Parthenon.”

But British experts have often claimed that Greece lacks a suitable place to preserve the marbles. When asked for a response to Tsipras’s latest request, the British Museum referred artnet News to a statement from its trustees on its website:

The British Museum tells the story of cultural achievement throughout the world, from the dawn of human history over two million years ago, until the present day. The Parthenon Sculptures are a significant part of that story. The Museum is a unique resource for the world: the breadth and depth of its collection allow a global public to examine cultural identities and explore the complex network of interconnected human cultures. The Trustees lend extensively all over the world and over 3.5 million objects from the collection are available to study online. The Parthenon Sculptures are a vital element in this interconnected world collection. They are a part of the world’s shared heritage and transcend political boundaries.

The trustees’ position paper also includes a list of “common misconceptions” about the Elgin marbles, including the belief that all of the sculptures from the Parthenon are in the British Museum. “This is incorrect,” they say. “About half of the sculptures from the Parthenon are lost, having been destroyed over the 2,500 years of the building’s history. The sculptures that remain are found in museums in six countries, including the Louvre and the Vatican, though the majority is divided roughly equally between Athens and London.”

The trustees also say it would be impossible to reincorporate the sculptures into the Parthenon. “Though partially reconstructed, the Parthenon is a ruin. It is universally recognized that the sculptures that still exist could never be safely returned to the building: they are best seen and conserved in museums. For this reason, all the sculptures that remained on the building have now been removed to the Acropolis Museum, and replicas are now in place,” the trustees write.

“We know Britain’s position but what has a particular value is that this effort is continued,” Tsipras told Reuters. “In due course, we’ll find increasingly more supporters of Greece’s just stance.”