Here is a timeline of Iranian-British relations:
1979 - Islamic Revolution overthrows U.S.-backed Shah.
1980 - Britain closes its embassy in Tehran after four British Christians were imprisoned in Iran and 72 Iranians were arrested in London after demonstrating outside the U.S. Embassy.
1988 - Britain restores full diplomatic relations with Iran.
February 14, 1989 - Iranian Supreme Leader Ayatollah Ruhollah Khomeini calls on Muslims to kill British author Salman Rushdie for blasphemy against Islam in his book "The Satanic Verses."
March 7 - Iran breaks diplomatic relations with Britain.
September 1990 - Partial diplomatic relations are restored.
April 28, 1994 - Britain accuses Iran of contacts with the outlawed Irish Republican Army. Iran denies this but relations worsen in June; Iran and Britain expel diplomats over the IRA.
Sept 24, 1998 - Iran formally dissociates itself from the call to kill Rushdie.
May 18, 1999 - Iran says relations between Tehran and Britain have been upgraded to ambassadorial level.
Sept 24, 2001 - British Foreign Minister Jack Straw visits Iran to strengthen an international "anti-terror" coalition after the September 11, 2001 attacks on the United States.
June 2004 - Iran arrests eight British military personnel for straying into its waters from Iraq. They are later freed.
October 12, 2005 - British Prime Minister Tony Blair says there is evidence that Iran or the Iran-backed Lebanese militia Hezbollah was the source of technology used in roadside bombs against British soldiers in Iraq. Iran denies involvement.
October 16 - Iran's president accuses Britain of being behind twin bombings that killed six people in southwestern Iran a day earlier, a charge Britain denies.
March 23, 2007 - Iranian forces seize eight Royal Navy sailors and seven marines from their patrol boat 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 2007 - Iran's Foreign Ministry summons the British ambassador to protest against the award of a British knighthood to author Salman Rushdie.
June 12, 2009 - Ahmadinejad's presidential election win is met by opposition accusations of vote-rigging and huge protests.
June 18 - Britain says it has frozen Iranian assets worth almost one billion pounds ($1.6 billion) under international sanctions imposed over Iran's disputed nuclear program.
June 19 - Britain protests to Iran about a speech by Supreme Leader Ayatollah Ali Khamenei in which he called Britain "the most treacherous" of Iran's enemies. Prime Minister Gordon Brown condemns violence and media restrictions in Iran.
June 23 - Britain expels two Iranian diplomats after Iran expels two British diplomats.
July 19 - Iran releases on bail the last of Britain's local embassy workers it had held, chief analyst Hossein Rassam. (Nine Iranian staff were detained in late June for alleged involvement in the post-election unrest.) Iran later tried Rassam on charges of espionage, which Britain described as an "outrage." The charges were dropped in October 2010.
December 29 - Iran summons Ambassador Simon Gass to the foreign ministry; he repeats Britain's position that Iran must respect its citizens' human rights, Britain's Foreign Office says. Foreign Minister Manouchehr Mottaki threatens Britain with a "slap in the mouth" if it does not stop interfering in Iranian affairs.
December 9, 2010 - Gass, on the embassy website, accuses Iranian authorities of depriving the people of "their fundamental freedoms."
December 13 - Lawmaker Kazem Jalali, spokesman for parliament's National Security and Foreign Affairs committee, says it will review ties with Britain on December 19. The committee's decision will be followed by a vote in parliament.
-- Jalali criticized the "impudent" behavior of Britain's ambassador. The Foreign Ministry has summoned him to protest against "violent and inhumane" policing of student protests in London, the semi-official Fars news agency reports.
November 21, 2011 - Britain imposes new financial sanctions on Iran, ordering all UK financial institutions to stop doing business with their Iranian counterparts and with the central bank of Iran.
November 28 - Iran's Guardian Council approves a parliamentary bill reducing ties with Britain within two weeks, which would force out the ambassador.
November 29 - Iranians storm the British embassy compound in Tehran and burn documents looted from offices, during a rally to protest against sanctions imposed by Britain, Iranian news agencies report. Britain says it is outraged by the incursion into the embassy grounds.
November 30 - Britain orders the closure of the Iranian embassy in London and expels its staff. It has also closed the British embassy in Tehran and all the staff have left Iran.
(Reporting by David Cutler, London Editorial Reference Unit)