The offer, officials said, is meant to persuade Iran to halt its push to produce fuel for a medical research reactor, the Washington Post reported.

 Iran on Tuesday started work to enrich nuclear fuel to a 20 percent to operate the reactor that produces medical isotopes. Iran needs medical isotopes for an estimated 850,000 patients.

 The move came after the International Atomic Energy Agency and the West failed to provide nuclear fuel to Iran’s medical reactor.

 “Rather than operate a reactor, this would be a more cost-effective and efficient approach,” one U.S. official said, speaking on the condition of anonymity.

The Foreign Office published an open letter from Britain”s Ambassador to Tehran, Simon Gass, to a senior Iranian member of parliament in response to recent calls by some Iranian parliamentarians to cut ties with Britain, Reuters reported.

In the letter to Alaeddin Boroujerdi, chairman of the Majlis Foreign Policy and National Security Committee, Gass said any decision by parliament to downgrade relations with Britain “would be regrettable.”Iran has accused Britain of fomenting post-election protests. Gass refuted the charge that Britain or its embassy were involved in the unrest.In late December, Iran summoned Gass and Foreign Minister Manouchehr Mottaki threatened Britain with a “slap in the mouth” if it did not stop interfering in Iranian affairs.