Greece insisted Monday that Britain return for good the Parthenon Marbles that have been in British possession for two centuries, adding negotiations about their fate were "not easy."
The ancient sculptures, also known as the Elgin Marbles, were taken from the Parthenon temple at the Acropolis in Athens in the early 19th century by British diplomat Thomas Bruce, the earl of Elgin.
"The objective is their definitive return," government spokesman Yiannis Oikonomou told a news briefing.
Greece "does not recognise the British Museum's possession and of course ownership of the sculptures. It has always been Greece's position," he said.
Britain's Daily Telegraph newspaper reported last week that the marbles could soon be returned as part of a "cultural exchange" being negotiated with Athens.
The deal, effectively a loan agreement, could see the 2,500-year-old antiquities returned "sooner rather than later", the Telegraph newspaper reported.
Such an arrangement could circumvent a legal ban on the museum breaking up its vast collection.
It would likely involve some objects being sent by London on a long-term loan basis with Athens reciprocating with some ancient Greek treasures.
Any loan deal, however, is not expected to end the long-running dispute over the 17 sculptures and part of a frieze.
The Telegraph said that Greece intends to keep up pressure to secure full legal ownership of the sculptures.
"We have come a long way. We have made steps and efforts continue. The negotiations are not easy," Oikonomou said.
Taken by Elgin when he was the British ambassador to the Ottoman Empire, Greece maintains the marbles were stolen and has long campaigned for their return while the UK maintains they were legally taken.
Their return remains a highly sensitive subject as the British Museum's vast collection includes many items now considered by other countries as loot taken by builders of the British Empire and the government is wary of setting a precedent.
A spokesperson said on Wednesday: "We've said publicly we're actively seeking a new Parthenon partnership with our friends in Greece and as we enter a new year constructive discussions are on-going."