British counter-terrorism police have arrested eight men including seven Iranians in two separate operations, officers said, in what the interior minister called some of the biggest investigations of their kind in recent years.

Seven Iranian nationals are among eight men arrested in two major counter-terrorism investigations that took place separately on Saturday. Five of the arrests were part of a "pre-planned" investigation into an alleged plot to "target a specific premises",

British police on Sunday said they had arrested five men, including four Iranians, on suspicion of "preparation of a terrorist act".The men, aged 39, 44 and 55, were arrested under the National Security Act -- which gives law enforcement greater powers to disrupt "state threats" including foreign interference and espionage -- the Met Police said in a statement on Sunday.