The deputy director of the British Museum has proposed a “Parthenon partnership” with Greece that could see the marbles returned to Athens after more than 200 years.

The sculptures – 17 figures and part of a frieze that decorated the 2,500-year-old Parthenon temple on the Acropolis – were taken by Lord Elgin in the early 19th century when he was the British ambassador to the Ottoman empire, and have since been the subject of a long-running dispute over where they should be displayed.

In an interview with the Sunday Times Culture magazine, Jonathan Williams said the British Museum wanted to “change the temperature of the debate” around the marbles.

Williams said: “What we are calling for is an active ‘Parthenon partnership’ with our friends and colleagues in Greece. I firmly believe there is space for a really dynamic and positive conversation within which new ways of working together can be found.”

The British Museum has not said it will hand the sculptures back, with Williams arguing they are an “absolutely integral part” of the collection.

However, he said they “want to change the temperature of the debate”, adding that all sides needed to “find a way forward around cultural exchange of a level, intensity and dynamism which has not been conceived hitherto”.

He added: “There are many wonderful things we’d be delighted to borrow and lend. It is what we do.”

The Greek prime minister, Kyriakos Mitsotakis, has called for the Parthenon marbles to be returned to Greece on many occasions, even offering to loan some of his country’s other treasures to the British Museum in exchange.

Mitsotakis has restated that Greece is open to negotiations but said: “Baby steps are not enough. We want big steps.”

The director of the Acropolis Museum, Nikolaos Stampolidis, said there could be a “basis for constructive talks” with the “positive Parthenon partnership” offer.

He added: “In the difficult days we are living in, returning them would be an act of history. It would be as if the British were restoring democracy itself.”