British-Iranian relations, which have been strained for decades, were back in the spotlight after Iranian authorities executed British-Iranian national Alireza Akbari for spying, charges he had denied.
Here is a timeline of main bilateral developments since the 1950s:
1953 - Britain and the United States help orchestrate the overthrow of popular Prime Minister Mohammed Mossadegh and restore Shah Mohammed Reza Pahlavi to power.
1979 - Islamic Revolution overthrows the US-backed Shah.
1980 - Britain closes its embassy in Tehran.
1988 - Britain restores full diplomatic relations with Iran.
February 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", prompting Britain to break diplomatic relations in March.
1990 - Partial diplomatic relations are restored.
1994 - Britain accuses Iran of contacts with the outlawed Irish Republican Army, a charge Iran denies but relations worsen. Iran and Britain expel each others' diplomats over the IRA issue.
1998 - Iran formally dissociates itself from the call to kill Rushdie.
1999 - Iran says relations between Tehran and Britain have been upgraded to ambassadorial level.
September 2001 - British Foreign Minister Jack Straw visits Iran to strengthen an international "anti-terror" coalition after the Sept 11, 2001 attacks on the United States.
2004 - Iran arrests eight British military personnel for straying into its waters from Iraq. They are later freed.
2005 - Britain says there is evidence Iran or the Iran-backed Lebanese militia Hezbollah was the source of technology used in roadside bombs against British soldiers in Iraq, a charge Tehran Iran denies. The same year, Iran accuses Britain of being behind bombings that killed six people in Iran. London denies it.
March 2007 - Iranian forces seize eight Royal Navy sailors and seven marines from their patrol boat in the Shatt al-Arab waterway separating Iran and Iraq. They are freed in April.
June 2007 - Iran's Foreign Ministry summons the British ambassador to protest against the award of a British knighthood to Salman Rushdie.
June 2009 - Britain freezes Iranian assets under Western sanctions imposed over Iran's disputed nuclear programme. The same month, Britain protests to Iran after Supreme Leader Ayatollah Ali Khamenei calls Britain "the most treacherous" of Iran's enemies. London and Tehran each expel two of the other's diplomats.
July 2009 - Iran releases on bail the last of nine Iranians who worked at the British embassy and who had been detained in June for alleged involvement in unrest following an Iranian election.
2011 - Britain imposes financial sanctions on Iran, ordering all UK financial institutions to stop doing business with Iranian counterparts and Iran's central bank. Iran's Guardian Council approves a parliamentary bill reducing ties with Britain.
November 2011 - Britain shuts Iran's embassy in London and expels its staff, saying the storming of the British mission in Tehran that month could not have taken place without consent from Iran's authorities.
2015 - Iran reaches a nuclear deal with the United States, Britain, France, Germany, Russia and China. Under the agreement Iran accepted curbs on its nuclear programme in return for a lifting of many foreign sanctions. Iran reopens its embassy in London hours after Britain restores diplomatic ties.
April 2016 - Iran detains British-Iranian aid worker Nazanin Zaghari-Ratcliffe, who was employed by the Thomson Reuters Foundation, a charity operating independently of Thomson Reuters and its news subsidiary Reuters. She is later convicted of seeking to overthrow the clerical rulers, a charge she denied.
May 2019 - Twitter suspended Iranian Supreme Leader Ayatollah Ali Khamenei's account over a tweet that said Khomeini's fatwa against Rushdie was "solid and irrevocable".
March 2022 - Zaghari-Ratcliffe and another British-Iranian dual national, Anoosheh Ashoori, return to Britain from Iran.
August 2022 - Salman Rushdie is stabbed on stage at a literary event in New York state. Iran's Foreign Ministry says no one has the right to level accusations against Tehran. Several Iranian hardline newspapers praise Rushdie's attacker.
October 2022 - Britain imposes sanctions on three Iranian military figures and a defence manufacturer for supplying Russia with drones used to attack targets in Ukraine.
November 2022 - The head of Britain's domestic spy agency says Iran's intelligence services have made at least 10 attempts to kidnap or kill British nationals or individuals in Britain.
December 2023 - Iran's Revolutionary Guards arrest seven people with links to Britain over anti-government protests.
January 2023 - Iran sentences to death and executes British-Iranian national Alireza Akbari, a former Iranian Defence Ministry official, on charges of spying for Britain. State media say he was involved in the 2020 assassination in Iran of a top nuclear scientist. Akbari denied the charges.