British counter-terrorism police have secured warrants to extend the detention of seven Iranian nationals arrested on Saturday in two separate cases, which the interior minister described as among the most significant investigations of their kind in recent years.

Authorities secured warrants to detain four Iranians aged between 29 and 46 - who were arrested over a suspected plot to target a specific premises - for questioning until May 10, London's Metropolitan Police said on Monday. Police have not named the targeted site.

"Our officers and staff are progressing what is a significant and highly complex investigation, and we still have searches and activity underway at multiple addresses across the country," Commander Dominic Murphy, who heads the Met's Counter Terrorism Command, said.

Britain has recently intensified its scrutiny of Iran, placing Tehran on the highest tier of its foreign influence register. Last year the head of MI5 domestic spy agency, Ken McCallum, said that since 2022, officers had responded to 20 Iran-backed plots, which potentially posed lethal threats to British citizens and residents.

Interior minister Yvette Cooper said on Sunday that the two counter-terror probes - which police say are not connected - reflected "some of the biggest counter state threat and counter terrorism operations that we have seen in recent years."

The operations reflected the complexity of the kinds of challenges to national security that Britain continued to face, she said on Sunday, when police announced the arrests.

A fifth man who had been arrested as part of the first investigation has now been released on bail, with conditions, to a date in May, the statement said.

In the second investigation, three men aged between 39 and 55 - also Iranian nationals - who were arrested on Saturday for suspected involvement in foreign power threat activity, are to be detained until May 10, the police force said.
 

Copied