Iran's Cultural Heritage Organisation said in October it had set a two-month deadline for the British Museum to allow the public display in Iran of the so-called Cyrus Cylinder, linked to the Persian ruler's 6th century BC conquest of Babylon.
The Museum, which houses a vast collection of world art and artefacts, said in September that plans to hand over the 2,500-year-old clay cylinder had been delayed due to unspecified "practicalities".
"If we find out for certain that the British Museum does not want to send the Cyrus Cylinder to Iran and is simply trying to kill time, we will cut all our ties with that organisation," the daily Arman quoted Hamid Baqaie, head of Iran's Cultural, Handicraft and Tourism Organisation, as saying.
"We will also ask all international cultural organisations, such as the UNESCO, to reconsider ties with the British Museum for not honouring their commitments."
No one at the British Museum was available to comment.
Iran's disputed presidential election in June plunged the country into political turmoil, with street protests that have turned into violent clashes with security forces.
Iran is already at odds with Britain and other Western powers over the Islamic state's nuclear energy programme, which the West suspects is for military aims. Iran denies this, saying it aims solely to produce electricity.
Cyrus is regarded as one of ancient Persia's greatest historical figures, creating one of the world's first empires two centuries before Alexander conquered the region.
Cyrus won Babylon in today's Iraq in 539 B.C. and freed Jews held in captivity there. He is also credited with authoring a decree inscribed on the cylinder named after him, which some have described as the first charter of human rights.
(Editing by Louise Ireland)
