TEHRAN -- Britain's new ambassador to Iran, Richard Dalton, took up his post Sunday, closing the door on a lengthy diplomatic stand-off which erupted when the Islamic Republic refused to accept another nominee, the British Embassy said.

Dalton takes over in Iran from Nick Brown, who left the country in December 2001.

Charge d'Affaires Neil Crompton has been running the embassy in the interim period, which included a high-profile visit to Tehran in October by Britain's Foreign Secretary Jack Straw.

An embassy spokesman said a date had yet to be set for the formality of Dalton presenting his credentials.

Dalton, a Middle East expert and former consul general in Israel, has been the country's ambassador to Tripoli since December 1999.

In February, Tehran refused to approve the appointment of David Reddaway, souring relations between the two countries. No reason was given for the veto.

Iran's refusal of Reddaway came a few days after U.S. President George W. Bush, whose main ally is Britain, dubbed Iran a member of an "axis of evil" along with Iraq and North Korea.