The leader of the UK’s labour party, Jeremy Corbyn, is the latest public figure to declare that colonial-era objects that were taken unlawfully should be returned to their country of origin. If elected prime minister in the next general election, which will take place in 2022, Corbyn has pledged to return the famous Parthenon Marbles to Greece.

Also known as the Elgin Marbles, the fifth-century sculptures—made under the sculptor Phidias—were taken from the Parthenon, an ancient temple dedicated to the goddess Athena that is situated on the Athenian acropolis, by Scottish nobleman Lord Elgin, who served as the Ottoman ambassador in the early 1800s.

The fate of the works, which have been housed in the British Museum in London since 1816, has been a source of tension between the two countries for decades. Greece has tried to retrieve the marbles numerous times. It has even threatened legal action and involved UNESCO. However, the museum maintains that the works were legitimately acquired since Elgin had received a special decree from the Ottoman government that allowed him to remove the sculptures and transport them to his home in Scotland before he sold them to the British Museum.

Greece has been demanding the return of the national treasures since it became independent from the Ottoman Empire in 1832 and will continue to pressure the British Museum to restitute them. When Athens opened its new Acropolis Museum in 2009, it left areas within its galleries empty in anticipation of the return of the Elgin marbles.

In an interview with the Greek newspaper Ta Nea, Corbyn said that Britain should be engaging in “constructive talks” with the Greek government about the return of the works. His remarks come on the heels of UNESCO’s call for dialogue between the two nations in order to find “a mutually acceptable solution.” Twelve countries, including France, backed the organization’s position on the issue.

In order to address the controversy and further explain its stance, the British Museum dedicated a portion of its website to the works. It reads “Within the context of this unparalleled collection, the Parthenon sculptures are an important representation of the culture of ancient Athens. Millions of visitors admire the beauty of the sculptures each year—free of charge. They also gain insights into how ancient Greece influenced and was influenced by the other civilizations that it encountered.”

It continues by arguing that the sculptures “are part of everyone’s shared heritage and transcend cultural boundaries. The trustees remain convinced that the current division allows different and complementary stories to be told about the surviving sculptures, highlighting their significance for world culture and affirming the universal legacy of ancient Greece.”