The random road-blocks, the first deployed by the police, began two weeks ago after the discovery of lorry bombs in Stoke Newington, north-east London, and at Canary Wharf, in Docklands, followed by the dumping of an escape vehicle at Bethnal Green, east London, which appeared to suggest the terrorists had a base on the eastern side of London.
In anticipation of another attempted attack at the weekend, Scotland Yard and the City of London police mounted Operation Rolling Rock, an operation to swamp the City and east London with a number of static checkpoints on main roads. The operation involved 45 uniformed officers, specialist marksmen and dog handlers. At the checkpoints, drivers were channelled into one lane and certain vehicles stopped and inspected. A total of 83 were stopped. Officers wore body armour and were backed up by high- speed pursuit cars ready to chase any vehicles that turned away or attempted to burst through the road-block. Police declined to say how many road-blocks were deployed, but up to 20 have been sited over the past couple of weeks.
Scotland Yard made it clear that the measure was designed to satisfy public concern that the police were going on the offensive against the IRA, as well as trap terrorists. 'The operation was mounted in an effort to arrest and detain terrorists as well as reassure the public that steps are being taken to counter the terrorist threat,' Scotland Yard reported.
Sources said the random checks would continue until Christmas, but there was no intention that they would become permanant. Police anticipate that the IRA will continue to maintain pressure over the next few weeks, but have warned that the policy of shifting tactics means that any type of attack is possible.
The main targets of the road- blocks are large 'box-type' vans and heavy goods vehicles which are used to carry the huge bombs made from fertiliser chemicals which the IRA first employed on the mainland in April. Since the discovery in August of a plot to leave a number of vans at strategic sites, police throughout London have been on the alert for such vehicles, particularly those which look as though they have been recently resprayed, which led to the Stoke Newington discovery.
The Police and Criminal Evidence Act allows such checkpoints to be set up and vehicles searched if police are suspicious. Some senior police officers have expressed concern that officers can only carry out searches where they can claim suspicion and cannot simply stop and search at will.
Home Office sources yesterday denied reports that officials were engaged in discussions with senior officers on whether the law should be amended - a move that would require legislation, raise civil liberties issues and be portrayed as a victory for the IRA. 'We consider existing laws sufficient,' they said.
The road-blocks represent another increase in security levels which have been steadily tightened as the IRA has imported tactics from Northern Ireland.