Director General of MI5 Ken McCallum delivers the annual Director General’s Speech at Thames House, the headquarters of the UK’s Security Service, in London, Britain, Oct. 16, 2025. Photo: Jonathan Brady/Pool via REUTERS

British police arrested four men on Friday on suspicion of helping Iran’s intelligence services carry out surveillance of people and locations linked to the Jewish community in London.

Detectives said one of the men was Iranian, while three had dual British-Iranian nationality. The arrests were part of a “long-running investigation,” police added, indicating the men‘s alleged activities pre-dated the US and Israeli bombardment of Iran, which started last Saturday.

British lawmakers and the domestic spy agency MI5 have long warned of threats posed to Britain by Iran. Three Iranians were charged with offenses under Britain’s National Security Act relating to assisting a foreign intelligence service last May.

In a separate investigation last year, police arrested five men, four of them Iranian, over a suspected plot to target specific premises, which British media said was the Israeli embassy. They were later released without charge.

“The Jewish community and the wider public will understandably be concerned by today’s arrests. We continue to monitor the situation closely,” interior minister Shabana Mahmood said on X.

Police said the four detained men were aged between 22 and 55. Six others were also arrested on suspicion of assisting an offender, and police said searches were ongoing.

Speaking about the current Iranian conflict on Thursday, Prime Minister Keir Starmer warned that people would use it to divide the country.

“The government is reaching out to communities across the United Kingdom – Jewish and Muslim alike – making sure communities and places of worship have appropriate, protective security in place,” he told a press conference.

Illustrating the threat from Iran, Britain’s MI5 spy boss said that over two years from 2022-2024, his service and British police had responded to 20 Iran-backed plots to kidnap or kill British nationals or individuals based in Britain who were regarded by Tehran as a threat.

Britain also recorded a 4% rise in antisemitic incidents in 2025, making it the second-worst year on record, a charity said. Two men were killed last October during an attack on a synagogue in the northern English city of Manchester.