A group of men recently arrested in Britain had been planning an attack, officials said, a development likely to ramp up tensions between Israel and Iran.

Iran has “categorically” denied any involvement after a terror plot involving alleged Iranian men, including one from Swindon, was foiled.

Five Iranians suspected of plotting an attack on the Israeli embassy in London belong to a highly trained special operations unit, a former intelligence officer has suggested. The group who were arrested on suspicion of preparing an act of terrorism allegedly belong to Unit 840,