An exploding parcel bomb injured three women at Britain's driver and vehicle licensing agency on Wednesday, the strongest indication yet that a spate of letter bombs may be motivated by an extreme case of road rage.

It was the third attack in as many days on offices that have some connection to motoring. Six people were injured in those incidents, but police disclosed that there have been more attacks and more injuries in the past three weeks.

Britain has seen letter-bombing campaigns by the Irish Republican Army and animal rights extremists, and vehicle-related vandalism including explosive attacks on speed cameras have been reported.

But even Motorists Against Detection, an underground group that claims to have destroyed a thousand speed cameras, said it was appalled by the letter bombs.

"I completely condemn it," said a man who identified himself only as the group's director.

"It's like apples and oranges, isn't it? One is a metal object, another is a living entity."

One woman suffered minor burns and two others were treated for hearing injuries following Wednesday's explosion at the Driver and Vehicle Licensing Authority in Swansea, Wales.

"I was shaken, shocked and frightened," the burn victim said in a statement given to media. Her name was not disclosed.

The DVLA issues driver's licenses and collects the annual road taxes due from vehicle owners, conducting much of its business by mail.

The Association of Chief Police Officers said that seven such devices had been mailed in the past three weeks, causing minor injuries to eight people. It did not say whether it believed all the devices were part of a single campaign.

"The packages received so far have caused minor injuries, but could have been more serious," said Assistant Chief Constable Anton Setchell, who is the national coordinator for domestic extremism.

Bomb disposal experts destroyed another suspicious package in a controlled explosion in Portsmouth Wednesday morning, Hampshire police said. "At this stage it is not being linked to any of the postal bombs across the U.K.," said spokeswoman Sally Evans.

She gave no details about where the suspicious package was found.

On Monday, a woman was injured by an exploding parcel at the head office of Capita Group PLC in London. One of the company's numerous government contracts was for designing and running a system for enforcing the US$16 daily congestion charge imposed on motorists in central London.

Two people were injured Tuesday in an explosion at Vantis PLC in Wokingham, 40 miles southwest of London. A spokesman for the accounting company said the parcel was addressed to a client whom he refused to identify. News reports, however, said the company's clients included Speed Check Services, which provides digital speed-enforcement technology.

Thames Valley Police said they were investigating three letter bombs sent last month to companies in Oxfordshire and Birmingham. Each company received a small padded bag containing a crude explosive device; the back of one envelope bore the name of Barry Horne, an animal rights extremist who died in 2001 while serving an 18-year jail sentence for a firebombing campaign.

Kent Police said a resident in Folkestone, 70 miles southeast of London, suffered minor injuries on Saturday when a letter exploded as it was being opened.

On Jan. 28, Kent Police said a homemade device exploded at a home in Chatham, 35 miles southeast of London, causing minor injuries to a resident. Chief Inspector Peter Wedlake said it appeared to be "a very small, crude homemade device that may have contained some firework powder."

Kent police said they believed the Chatham incident was not related to the letter bomb campaign.

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