A network of suspected far-right extremists with access to 300 weapons and 80 bombs has been uncovered by counter-terrorism detectives.
Thirty-two people have been questioned in a police operation that raises the prospect of a right-wing bombing campaign against mosques.
Police are said to have recovered a British National party membership card and other right-wing literature during a raid on the home of one suspect charged under the Terrorism Act.
In England’s largest seizure of a suspected terrorist arsenal since the IRA mainland bombings of the early 1990s, rocket launchers, grenades, pipe bombs and dozens of firearms have been recovered in the past six weeks during raids on more than 20 properties. Several people have been charged and more arrests are imminent. Current police activity is linked to arrests in Europe, New Zealand and Australia.
Police are examining allegations that many of the guns were manufactured or reactivated, then sold over the internet to viewers of a right-wing website.
Details of the previously secret operation were disclosed by Sir Norman Bettison, the chief constable of West Yorkshire, to security officials.
Police sources say that in a recent case not linked to the current arrests, detectives seized maps and plans of mosques from the homes of suspected far-right supporters. A senior Whitehall official said MI5 was monitoring the police investigation.
While the security agency did not have a brief to probe right-wing terrorism, that position was constantly under review, said the official. Fears have been heightened by the discovery of an alleged plot involving ricin, a lethal poison; two men have been been charged with offences under the Terrorism Act. Concerns that this might be part of a global trend have been reinforced by the case of James Von Brunn, the 88-year-old white supremacist charged with shooting dead a security guard at the Holocaust museum in America last month.
Bettison said 32 people had been arrested in the investigation, although the counter-terrorism unit in Leeds said this figure was in fact the number of people questioned. At least 22 properties have been searched.
The operation had thrown up evidence that suspects were communicating online.
“The internet gives it reach and scope,” said Bettison. “The big bad wolf is still the Al- Qaeda threat. But my people are knocking over right-wing extremists quite regularly. We are interdicting it so that it doesn’t first emerge into the public eye out of a critical incident like an explosion.”
Several alleged right-wing extremists have been charged with terrorism offences in the UK in the past year.
In one case, a jury convicted Martyn Gilleard, 31, a neo-Nazi forklift truck driver, who wanted to “secure a future for white children” and kept explosives at his flat in Goole, East Yorkshire. He built small hand-held bombs, and among the material seized were membership cards for the National Front, the British People’s party and the White Nationalist party. He was sentenced to 16 years in prison.
In 1999, David Copeland, the so-called London nail bomber, carried out a campaign against black, Asian and gay communities. His home-made devices each included up to 1,500 4in nails. In his final attack Copeland killed three people, including a pregnant woman, after nail bombing a Soho pub. He got a life sentence for murder.
Far-right parties across Europe are growing in popularity. In last month’s European elections, the BNP won two seats for the first time in Yorkshire and the northwest and took 6.2% of the national vote.