A convicted arsonist who holds workshops on how to make firebombs faces being banned from entering Britain as part of a government crackdown on the extreme wing of the animal rights movement.

The move, thought to be the first ban of its kind against an animal rights activist, comes amid growing alarm that the movement is becoming increasingly violent in the UK. Figures obtained by The Observer show that attacks admitted by animal activists have risen almost 40-fold over the past two years, with the movement's leaders warning that their most concerted campaign of terror is yet to begin.

This year animal activists have committed more than 150 high-profile incidents in the UK, compared with four in 2002. The rise in violent attacks comes as Whitehall sources have revealed that MPs on the Commons select committee on science and technology have been targeted. Last week Ian Gibson, the committee chairman, said he had started checking under his car for bombs.

Last night, a spokesman for the Home Office said: 'We are examining statements made by a number of American activists. We have the right to exclude anyone we believe could be attempting to provoke or promote violence.'

Topping the list of activists concerning the Government is Rodney Coronado, a one-time member of the Animal Liberation Front in the US, who was jailed for 57 months in 1995 for the arson of a Michigan State University research laboratory. In November 2002 he also admitted to six other arsons in the US.

In recent years Coronado has started appearing at conferences held by Shac, the group campaigning to close down Cambridgeshire-based Huntingdon Life Sciences. Last year he gave a demonstration at American University, Washington, on how to make a firebomb out of household items including a milk bottle and a joss stick. Coronado has received more than $70,000 in legal funding from the charity People for the Ethical Treatment of Animals (Peta).

Last year, only 15 people were excluded from entering the UK. The government's decision to ban the Nation of Islam leader, Louis Farrakhan, from entering the country caused a storm of protest.

The government is also believed to be considering a ban for Jerry Vlasak. In an interview with The Observer last week Vlasak sparked outrage by saying: 'I think violence is part of the struggle against oppression. If something bad happens to these people [animal researchers], it will discourage others. It is inevitable that violence will be used in the struggle and that it will be effective.' He also stood by an earlier claim that: 'I don't think you'd have to kill too many [researchers]. I think for five lives, 10 lives, 15 human lives, we could save a million, 2 million, 10 million non-human lives.'

Amid the rising tide of violence and concerns that militant groups on both sides of the Atlantic are swapping information, tactics and personnel, UK intelligence agencies have started liaising with their counterparts in the US. The FBI has compiled a file on Robin Webb, UK spokesman for the Animal Liberation front.

Last week, in a sign that the government is becoming increasingly alarmed at the extremist tactics displayed by militants in the animal rights movement, it unveiled a package of measures designed to curb attacks on biotech companies and research laboratories. For the first time police officers will be able to arrest activists outside their targets' homes, while harassment laws are to be tightened up.

But both Shac and its splinter organisation, Speak, which campaigns to halt the construction of a new primate research laboratory in Oxford, claimed the measures would have no impact on their activities. Simon Lewis, an independent legal adviser to the groups, said: 'It appears to be an exercise in spin, an attempt to placate pharmaceutical interests.'

A Shac spokesman claimed that 51 suppliers and companies once connected to Huntingdon had severed their links with the firm.

The most recent major incident in the UK involved a massive arson attack on a Surrey laboratory last month.

In a further sign that Shac and its supporters were preparing to up the ante against Huntingdon, the group has revealed it is to switch its targets from Japanese companies with links to the UK firm to major British companies such as GlaxoSmithKline.