A letter bomb exploded at Britain's vehicle licensing agency Wednesday, injuring three women, in a spate of attacks targeting motoring-related organizations.

Police said seven devices had been sent through the mail in the last three weeks, including three bombs in the last three days. At least seven people have been injured.

Wednesday's blast at the Driver and Vehicle Licensing Agency (DVLA) in Swansea, south Wales, raised media speculation that an angry motorist had launched a campaign of letter bombs.

One woman was treated for cuts in Wednesday's attack. Three colleagues were sent to hospital with hearing injuries and two others were treated at the scene.

Attacks on Monday and Tuesday this week hit offices linked to companies involved in speed cameras and traffic fees.

"I am appealing today for companies, organizations and individuals to take extra care when handling mail," Assistant Chief Constable Anton Setchell said in a statement.

Kent police disclosed Wednesday that a 53-year-old man was injured when a letter exploded at his home in Folkestone, southeast England, on Saturday.

Home Secretary John Reid said the explosions were worrying. "It is important that we allow police to get on with their investigation without undue speculation," he said in a statement.

A letter bomb exploded at a business center in Berkshire, southern England, on Tuesday at the office of Vantis, a business services firm, injuring two men. Newspapers reported that the letter was addressed to "Speed Check Services" which supplies speed cameras to the police but was sent instead to its accountants.

On Monday, a woman was injured in a letter bomb explosion at the London headquarters of Capita, the firm managing London's congestion charge.

(China Daily via Agencies February 8, 2007)