Is a motorist with a grudge behind postal bomb attacks?

Two Jiffy bags have exploded within 24 hours at companies which help administer penalty tickets.

Last night, firms, councils and police forces linked to motoring fines were put on alert over concerns that more bombs could be in the post.

A blast yesterday left two male workers at the accountancy firm Vantis in Wokingham, Berkshire, with injuries to their hands and upper bodies.

The explosion came a day after a parcel exploded at the UK headquarters of Capita, which runs the congestion charge scheme in Central London. It injured a woman postroom worker.

All the victims' injuries were minor but detectives warn that the next victim could be seriously hurt.

Possible links to three letter bombs sent in January to addresses in Oxfordshire and Birmingham are being investigated. Officers previously thought they were sent by animal rights extremists.

Vantis handles accounts for road camera operator Speed Check Services. The bomb was addressed to SCS managing director Paul Davey.

His wife, Mary, said her husband phoned just after the device went off to warn her not to open the mail.

She said: "It was terrifying but we can't let this person win, so we will carry on as normal."

The firm, which is based in Camberley, Surrey, uses Vantis as its official registered office.

Vantis's address appears on SCS letters to motorists. It operates a network of SPECS digital cameras which catch speeding drivers out by reading their numberplates and measuring their average speed between two points.

Touted on the firm's website as "the ultimate deterrent", such cameras are partly responsible for the rising number of speeding tickets issued each year.

The Capita bomb – addressed to chief executive Paul Pindar – was opened in Victoria, Central London, on Monday morning.

The injured woman is still being treated for cuts to her stomach and hands but is making a good recovery.

More than two million fixed-penalty tickets are handed out each year, generating around £120 million.

They are triggered by more than 6,000 cameras administered by operators such as police forces and local "safety partnerships".

But many fine and debt collections are carried out by firms such as Capita. The rapid increase in fines for illegal parking, speeding or failing to pay tolls has angered many motorists and speed cameras have been vandalised, burnt and even stolen.

Anti-camera campaigner "Captain Gatso", director of Motorists Against Detection, said last night: "We're not responsible for these attacks and do not condone causing injury.

"However, there is a war against motorists and it seems this is an act of retaliation."

The five letter-bomb attacks are being investigated by the National Extremism Tactical Co-ordination Unit – a police squad that deals with domestic fanatics – with the help of anti-terror officers from Scotland Yard.

Is a motorist with a grudge behind postal bomb attacks?