Margaret Thatcher was in 10 Downing Street when the device exploded but was not hurt in the blast.One of her staff was slightly burnt in the attack. Four more bombs were sent to senior politicians but were intercepted before they got through.
Letters from a group called the Animal Rights Militia were in the Downing Street package but other groups promoting animal welfare have said they have never heard of this organisation.
The bomb – which was addressed to the prime minister herself – arrived at Number 10 in a padded envelope and immediately aroused suspicions.
The official responsible for handling such packages, office manager Peter Taylor, was handling it when it flared up, burning his hands and face. Mr Taylor was taken to the nearby Westminster Hospital but was discharged after a few hours and is now back at work.
Police said the device was gunpowder-based and was designed to burn rather than explode.
The remaining packages were sent to the leaders of the other major UK political parties and one government official. Mrs Thatcher, who was in her study when the bomb went off, told the House of Commons at Prime Minister’s Questions that all MPs should be on their guard.
“Letter bombs anywhere are most distressing and I’m afraid we are all vulnerable,” she said.
An investigation is now underway to discover how the package got through the rigorous checks performed on all mail sent to 10 Downing Street.
Groups like the Animal Rights Militia (Arm) and the Justice Department have been at the extreme end of animal rights campaigning since the early 1980s.
The activists – who use violence to further their cause – are thought to have links with more moderate groups like the Animal Liberation Front.
But many ALF members dislike their tactics, believing they taint their cause.