The home-made bomb is twice as big as the IRA device that devastated the Bishopsgate area of the City of London last year. It was discovered in hidden compartments welded on to the bottom of the truck during a security check at Heysham, near Morecambe, after someone became suspicious of the Leyland flat-bed vehicle which had arrived on a ferry from Warrenpoint, Northern Ireland, at dawn.
Detectives believe the bomb, which only needed a detonator and timer to set it off, could have been intended for the City or another high-profile mainland target such as the Channel tunnel.
About 200 workers were evacuated from the port and passenger ferries were diverted down the coast to Fleetwood.
In a separate incident in South Armagh yesterday, a military helicopter was forced to make an emergency landing after it was hit by a mortar bomb while taking off from a joint army and police base at Newtownhamilton. There were no casualties.
If the lorry bomb is confirmed as the work of the IRA it will cast fresh doubts on the republican movement's claimed commitment to a peace process. The latest incidents follow the IRA's murder of a leading loyalist, Ray Smallwoods, and an armed attack on the home of a Democratic Unionist MP, the Rev William McCrea. The shootings provoked fears of revenge attacks by loyalists. However, yesterday's annual Orange marches in Northern Ireland passed off peacefully.
Sinn Fein is due to hold a delegate conference soon to decide its response to the Downing Street peace declaration, prompting speculation that the republicans may be preparing to call a three-month ceasefire. Unionists predicted the conference would be preceded by an upsurge in violence. The RUC's Chief Constable, Sir Hugh Annesley, said some weeks ago that there was a serious risk of the IRA targeting British cities in its search for terrorist 'spectaculars'.
Last night, Lancashire police and officers from the Metropolitan Police's Anti-Terrorist Branch were looking for whoever was supposed to collect the lorry.
The explosives were found in two six-inch high compartments, measuring 24ft by 3ft and 24ft by 8ft, attached to the floor of the Leyland Freighter, registration number B459 VKP. Police want to know the movements of the truck before its arrival in Heysham. It has a white cab and its rear is partly painted black.
The Army last night praised the pilot of the RAF Puma downed in south Armagh for his 'great courage' in guiding the stricken aircraft away from several houses and a primary school. The helicopter was carrying a three-man crew and 12 members of a joint army and police patrol when it was hit by the mortar bomb.Reuse content