KEY POINTS:
LONDON - A national police alert was issued yesterday after the seventh letterbomb attack in three weeks.
Police suspect the public and postal workers are under threat from at least two terror campaigns - one by a disgruntled motorist and the other by animal rights extremists.
In the past month letterbombs, some containing gunpowder and glass, have been sent to seven addresses.
Five have detonated when opened, injuring eight people.
No one has yet been seriously hurt, but detectives fear that someone could soon by maimed or killed.
The latest blast happened yesterday at the Driver and Vehicle Licensing Agency in Swansea.
"I am appealing today for companies, organisations and individuals to take extra care when handling mail," said the national co-ordinator for domestic extremism, Assistant Chief Constable Anton Setchell, who is heading the investigation into possible links between the seven letters.
"If they have any suspicions about any letter or package, they should leave it unopened and call the police immediately."
Fears that a disgruntled motorist is behind the most recent attacks were apparently confirmed by the explosion at the DVLA - the agency that maintains registers of drivers and vehicles and collects car tax.
All incoming mail to the DVLA has been stopped in the wake of the blast.
There have been three letterbomb attacks in consecutive days on companies connected to tackling motoring offences in London, Berkshire and South Wales.
The latest blast happened at the DVLA's main centre in Swansea and left three women in hospital.
On Wednesday, a letterbomb containing glass fragments exploded at an accountancy firm linked to Speed Check Services, in Wokingham, Berkshire, a provider of digital speed cameras to the police.
That came after a letterbomb attack the day before at the central London offices of Capita, which runs London's congestion-charge system.
On Saturday, a letterbomb blew up at a house in Folkestone, Kent, injuring the 53-year-old man who opened it.
He is believed to be a security company manager responsible for providing door staff and security services to businesses. It is unclear if this attack is related to the three latest incidents.
The first three of the seven letter-bombs were sent to companies in Oxfordshire and the West Midlands area last month. They are being linked by Thames Valley Police.
In each case, the companies received a padded bag containing a crude firework-type explosive device.
Each had a similar return address, and Barry Horne, an animal rights extremist who died in 2001 while serving an 18-year jail sentence for a firebombing campaign, was named on the back of one envelope.
Two of the devices failed to detonate, but one sent to Orchid Cellmark, in the Chelmsley Wood area of Birmingham, caused minor injuries to a woman who opened it.
Keith Ashcroft, a forensic psychologist, said the fact that the packages were being delivered to a wide range of organisations involved in dealing with motoring offences suggested "a frustration response that they can't express their anger and they want to create mass panic".
He added: "It is possible that someone who is frustrated with other aspects of their life is channelling their hate, rather than a specific vendetta.
"I'm thinking that they have a troubled background and they are picking on a case to make them notorious."
He said it was more likely to be an individual responsible than a group, as it would be difficult to get a number of people to agree to such activities."
John Potter, a consultant psychologist, said the culprit would probably continue acting as they normally would, but would feel increasingly tempted to tell someone about their actions.
- INDEPENDENT
