A second letter bomb in two days exploded in Britain today, injuring two men a day after a similar device hurt a woman.
Police said they were investigating possible links between the blasts and checking whether either or both were connected to a suspected campaign by animal rights extremists.
Britain has some of the world's most militant animal rights campaigners whose tactics have previously involved letter bombs.
Bomb disposal officers and paramedics were called to a business centre in Berkshire, southern England, today after employees reported a small explosion at the office of Vantis, a business services firm.
"It is likely an item of mail ignited and caused the injuries," police said in a statement. Detectives from Thames Valley Police were examining whether the bomb was linked to the device which exploded the day before at the London headquarters of Capita, the firm managing London's congestion charge.
That blast injured a woman at the company which collects 25 million payments a year from motorists who pay to drive into central London. Police were also considering whether the two incidents were connected to three other recent letter bombings.
On January 18th, two incendiary devices were sent to businesses near Abingdon, central England, one of which exploded. Another was found at a company in Birmingham the following day. "We were linking all three of those and at the time we came out with a statement that we were fairly confident it was as a result of animal rights," a police spokeswoman said. "Whether that still stands up, we will see."
Two of January's letter bombs bore the names of animal rights activists. One named Barry Horne, who died in prison in prison in 2001 while serving a jail term for plotting a nationwide firebomb campaign. In January 2001, there was a spate of letter bomb attacks on shops and small businesses which were blamed on animal rights extremists.
Vantis employs more than 1,000 people in 19 locations in England and provides accountancy, outsourcing and tax compliance services.
A company spokesman said the package was not addressed to Vantis and denied media reports the firm was involved in collecting motorist speeding fines. An ambulance service spokesman said paramedic teams treated two male members of staff in their 30s for blast injuries to their hands and upper body.