The National Criminal Intelligence Service (NCIS), which gathers police information on hooligans, also claims that the Chelsea 'Headhunters', who currently number up to 100, are often recruited by hooligan supporters of other clubs for battles with rival fans.
At a press briefing to mark the start of the new football season, Superintendent Adrian Appleby, head of the Football Unit at the NCIS, said the Chelsea fans were among about 500 hooligans identified as being involved in orchestrated violence with other fans or the public away from grounds.
Many followed teams for the hooliganism and did not actually attend matches. Football supporting was also used as a cloak for activities such as assault, robbery, rape and fraud.
Although arrests at grounds had remained static last year at about 6,300, Supt Appleby said police were concerned that the public should not be lulled into a false sense of security. Much violence occurred away from grounds and was not obviously linked to football, and he acknowledged that success in limiting violence around grounds could have led to some displacement.
About 20 of the Chelsea Headhunters were of particular interest to police. 'They have no visible means of support, but they travel club class around the world to places like Australia and Bangkok in support of England. When they are arrested they give their occupation as 'company director' yet they have never done a stroke of work in their life.'
Usually in their late twenties or thirties, they wore smart casual clothes and did not display tattoos; most were members of the extreme right-wing British National Party. Many were among the younger or less active hooligans not arrested in police operations during the mid-1980s.
Doubts about police evidence in those cases led to the collapse of one trial and the freeing of a number of people when their convictions were quashed on appeal. Supt Appleby said this had created a mythology that the Headhunters were 'untouchables'.
When Heart of Midlothian played in Belgium recently, hooligans among their supporters called up the Headhunters, Supt Appleby said. Thirty of them went to support the Scottish team and became involved in various acts of violence, he added. There was also evidence of involvement with supporters of non-league clubs.
The Edinburgh club was one of a number targeted in a BNP recruitment campaign. Others were Chelsea, Glasgow Rangers, Blackburn, Burnley and Oxford United.
The hard core were devoted fans who also happened to be criminals: 'I think they were originally football fans - the club is their religion. But they would have been criminals if there was no football.'
Foreign trips following their clubs or England were used to buy equipment such as CS gas, thunder flashes and flares which could not be bought in this country. Although the unit always warned other countries about the fans, Supt Appleby was concerned that those arrested abroad were deported by local police rather than charged. 'I have individuals on our computer who always buy single tickets, knowing they will have their fare paid coming back by going out deliberately to cause trouble so they are arrested and deported. There are individuals who have not got a conviction but have been deported from six countries.'
About a dozen women were among the 5,500 'second-rank' hooligans on the unit's computer. Many were used by male hooligans to carry weapons.
The unit liaises with 93 football intelligence officers based round the country and those in other countries; it has a portable Photophone, which can transmit photographs of known offenders to be checked instantly.