Britain is expelling two Iranian diplomats after Iran forced two British diplomats to leave, Prime Minister Gordon Brown said on Tuesday.
Following is a timeline of British-Iranian relations since the 1979 Islamic revolution in Iran:
1980 - Britain closes its embassy in Tehran.
1988 - Britain restores full diplomatic ties with Iran.
Feb 14, 1989 - Iranian revolutionary leader Ayatollah Ruhollah Khomeini calls on all Muslims to kill British author Salman Rushdie for blasphemy against Islam in his book "The Satanic Verses". Britain pulls out mission staff in protest.
March 7 - Iran breaks diplomatic relations with Britain.
Sept. 1990 - Partial diplomatic relations are restored to the level of deputy head of mission or charge d'affaires.
April 28, 1994 - Britain accuses Iran of having secret contacts with the outlawed Irish Republican Army, which Iran denies. Diplomatic ties worsen on June 1 when Iran and Britain expel diplomats over the IRA row.
Sept 24, 1998 - Iran formally dissociates itself from the death edict against Rushdie.
May 18, 1999 - Iran says relations between Tehran and Britain have been upgraded to ambassadorial level.
Jan 10, 2000 - Iranian Foreign Minister Kamal Kharrazi visits London, the first official visit by an Iranian minister since the 1979 Islamic Revolution.
Sept 24, 2001 - British Foreign Minister Jack Straw visits Iran to bolster an international "anti-terror" coalition after the Sept. 11, 2001 attacks on the United States.
Feb 7, 2002 - Tehran rejects David Reddaway as London's new ambassador, calling him a spy, forcing London to name a new envoy.
June 21, 2004 - Iran arrests six Royal Marines and two naval personnel -- part of the U.S.-led force in Iraq -- for straying into its waters. They are released after negotiations.
Oct 12, 2005 - Prime Minister Tony Blair says there is evidence that Iran or the Iran-backed Lebanese militia group Hezbollah was the source of sophisticated technology used in roadside bombs against British soldiers in Iraq. Iran denies any involvement.
Oct 16 - Iran's president accuses Britain of being behind twin bombings that killed six people in southwestern Iran a day earlier, a charge that Britain denies.
March 23, 2007 - Iranian forces seize eight Royal Navy sailors and seven marines, in the mouth of the Shatt al-Arab waterway that separates Iran and Iraq.
April 4 - President Mahmoud Ahmadinejad says he will free the 15 as a "gift" but scolds Britain for not being "brave enough" to admit they had made a mistake and strayed into Iranian waters. They arrive back in Britain the next day.
June 24, 2007 - Iran's parliament speaker says the award of a British knighthood to author Salman Rushdie, was a shameless act. Iran's Foreign Ministry summoned Britain's ambassador to Tehran the previous week to protest against the honour.
June 18, 2009 - Britain says it has frozen total Iranian assets of almost a billion pounds under international sanctions imposed over Tehran's disputed nuclear programme.
June 19 - Britain protests to Iran over a speech by Supreme Leader Ayatollah Ali Khamenei who called Britain "the most treacherous" of Iran's enemies. Prime Minister Gordon Brown has condemned violence and media curbs in Iran after the disputed June 12 presidential election, led to days of protests.
June 21 - Iran says it will expel BBC correspondent from Tehran over the broadcaster's coverage of election,
June 23 - Britain expels two Iranian diplomats after Iran forced two British diplomats to leave.
(Writing by David Cutler, London Editorial Reference Unit)