The British Museum expressed "great surprise" on Sunday at Iran's announcement that it was cutting ties with the London institution over delays in the loan to Tehran of an ancient Persian treasure.

The museum said it had confirmed its intention to lend the Cyrus Cylinder and associated fragments of clay tablet to the National Museum of Tehran in the second half of July during a phone call to Iranian officials on 2 February.

This was followed up with an email and faxed letter to Hamid Baghai, who heads Iran's cultural heritage and tourism organisation, on 5 February.

"The new announcement from Mr Baghai therefore comes as a great surprise," the museum said in a statement.

"The British Museum has acted throughout in good faith, and values highly its hitherto good relations with Iran. It is to be hoped that this matter can be resolved as soon as possible."

The British Museum's commitment

An official at Iran's cultural organisation said it cut ties after the museum failed to meet a final deadline for the loan on Sunday and said it would complain to the UN Educational, Scientific and Cultural Organisation (UNESCO).

Many historians regard the cylinder, discovered in 1879, as the world's first declaration of human rights.

"The British Museum has a long standing policy of lending its unparalleled collection as widely as possible across the world to benefit the greatest number of world publics," the institution added.

"This cultural exchange is a vital part of the museum's commitment to being a museum for the world.

"The trustees reaffirmed their view that exchanges of this sort were an essential part of the museum's international role, allowing valuable dialogues to develop independently of political considerations."