Days after the Vatican signed an agreement to return three Greek sculpture fragments that have been part of the Vatican Museums’ permanent collection for 200 years, Britain’s prime minister, Rishi Sunak says the Greek sculpture remain a “huge asset” to the UK.

Sunak has vowed to protect the Parthenon marbles from being returned to Greece, sticking by commitments made by his predecessors Liz Truss and Boris Johnson to safeguard the treasures at the British Museum in London.

Despite a campaign to return the marble sculptures to Athens, and talks between officials in the UK and Greece about the idea, it was given short shrift by Sunak.

“The UK has cared for the Elgin marbles for generations,” Sunak said. “Our galleries and museums are funded by taxpayers because they are a huge asset to this country.

“We share their treasures with the world, and the world comes to the UK to see them. The collection of the British Museum is protected by law, and we have no plans to change it.”

The marbles have been displayed in the British Museum since 1832 after being controversially stripped from the Parthenon by Lord Elgin, a British diplomat.

Greece has long said the marbles should be returned to the country permanently. However, the British Museum’s firm position is that any potential agreement would involve items being returned on loan.

Ministers are said to have no intention of amending the British Museum Act, which prevents the museum from returning any of its collection permanently except in very limited circumstances.

The Vatican fragments will be transferred to Athens on 24 March with a special ceremony planned to receive them.