AN IRISH republican terror cell is operating in England for the first time in a decade, creating a growing security problem in the weeks before the royal wedding.
Counter-terrorism teams in southern England have been diverted from tracking Islamist cells to examining a potential threat, The Times has learnt. And Cobra, the British government's national emergency committee, has increased its occasional meetings in Whitehall to three a week, with some chaired by Prime Minister David Cameron.
There are two months until the wedding of Prince William and Kate Middleton; President Barack Obama arrives for a state visit in May; and the London Olympics begin in 18 months.
An attack is not believed to be imminent, however, and the dissident unit is not considered to be as immediately dangerous as a number of home-grown Islamist terror cells with links to al-Qa'ida. Some of these groups are known to be plotting a terror attack in the style of the Mumbai assault of 2008, when more than 170 people were killed in a series of co-ordinated shootings and bombings.
Last week, police and soldiers took part in an exercise which mocked up the possibility of simultaneous terrorist gun attacks in Birmingham and Reading. The exercise included an emergency meeting chaired by Theresa May, the Home Secretary.
The Times also understands that armed anti-terrorist units were scrambled on New Year's Eve in response to fears that an attack by an Islamist group was imminent. The incident was quickly found to be a false alarm and the teams were stood down.
Until recently, the dissident Irish republican threat had been confined to Northern Ireland and the security assessment was that the different factions were too small, inexperienced and lacked the capability to operate outside Northern Ireland. A Real IRA bombing campaign in 2001 was the last time republican groups exported terror across the Irish Sea.
Hugh Robertson, the Olympics Minister, said last week that dissident Irish republican groups were regarded as a real threat to security at the Games. A counter-terrorism source said: As the Games get closer the appetite for risk will diminish. The plan will be to disrupt and deter plots, making sure they don't get off the ground, rather than letting them run to gather evidence and get convictions in court.
Recent incidents in Northern Ireland have involved car bombs and anti-personnel devices which have usually been preceded with coded, though often confused, telephone warnings to the authorities. They have also, however, targeted individuals with booby traps. The threat level for Irish terrorism in Britain was raised last September from moderate to substantial , meaning an attack was a strong possibility. At the time Jonathan Evans, MI5 director-general, said that the dissident groups posed a real and rising security threat.
The threat level for al-Qa'ida-linked terrorism is currently at severe , meaning that an attack is highly likely. The Islamist danger is, however, feared to be changing in character.
One plot being investigated by British, American and other international agencies is for simultaneous armed attacks in Britain, France and Germany. British police are particularly concerned after the case of a former American Marine who allegedly smuggled handguns into Britain on transatlantic flights. Sixty weapons are believed not to have been recovered.