Parthenon marbles loaned to Russian museum

Part of the Parthenon marbles have been allowed to leave Britain for the first time through a loan of a sculpture to a Russian museum.

The headless statue of a Greek river-god, Ilissos, will go on display in the State Hermitage Museum in St Petersburg on Friday to help celebrate the institution’s 250th anniversary.

The marbles have been held by the British Museum since Lord Elgin, the British ambassador to the Ottoman empire, took them from the Parthenon in Athens in the 19th century.

Neil MacGregor, director of the British Museum, said it opened its doors five years before the Hermitage and that the two institutions were “almost twins, they are the first great museums of the European Enlightenment”.

He added: “The British Museum is a museum of the world, for the world and nothing demonstrates this more than the loan of a Parthenon sculpture to the State Hermitage.”

The decision is likely to cause controversy given the frosty relations between Russia and the west in the wake of the invasion of eastern Ukraine earlier this year and the shooting down of Malaysia Airlines flight MH17 in July, killing all 298 people on board.

MacGregor told the Times: “The politics of both museums have been that the more chilly the politics between governments, the more important the relationship between museums.”

The loan was only agreed a fortnight ago. Sir Richard Lambert, the chairman of the British Museum’s trustees, said that they wanted to “leave room for flexibility if the political relationship between western Europe and Russia changed”.

The two-month loan will also reopen the debate about whether the marbles should be returned to Greece. The Greek government has argued for the past four decades that the 2,500-year-old sculptures belong in a museum in Athens. The British Museum is the most generous lender in the world, MacGregor said.

However, no talks had ever been held with the Greek government about a loan of part of the Parthenon marbles. “To date they have always made it clear that they would not return them. That rather puts the conversation on pause,” the director said.

• The headline of this article was amended on Friday 5 December 2014 to reflect Guardian style.