A law designed to combat stalkers has been used to impose temporary injunctions on a group of anti-war activists.

They are alleged to have conducted a campaign of unlawful harassment against defence industry management and staff.

EDO MBM Technology Ltd managing director David Jones launched the High Court action on behalf of 156 employees at the Brighton plant who claim they have been subjected to assault, intimidation and insults from protesters.

Mr Justice Gross said the primary intention of the Protection from Harassment Act was to deal with stalking but it had already been used in cases involving animal rights and GM crop protests.

Protesters today claimed the move would have a draconian impact on the rights of free association, expression and protest.

Alistair Arthur, 26, said: "This ruling has brought the burden of proof for harassment so phenomenally low.

"A company can now just buy an injunction and dictate the terms of protest for anyone who objects to what they do. It is a ridiculous situation."

Andrew Beckett, 30, said: "This injunction, even though it wasn't in quite the terms that EDO wanted, is still a draconian assault on our civil liberties.

"But we are now part of the biggest protest movement in British political history and nobody can doubt that the war against Iraq was illegal.

"We will not allow our right to protest against those who have been ancillary to these war crimes to be infringed.

The judge said: "Great care needs to be taken in applying the Act to situations of public protest."

But he could not accept argument from the protesters that strict limits should be set on the use of the Act.

All the protesters seemed willing to commit criminal acts in pursuit of their campaign against the claimants, he said.

There was a real risk the defendants would join in activities which would result in harassment of the claimants.

The injunction, which will last until the full trial of the action, imposes limitations on any protest with an exclusion zone around the EDO premises.

EDO, a weapons factory which makes parts for warplanes, claims it has been targeted in a concerted campaign of unlawful harassment, with employees assaulted, intimidated and insulted.

A road block at the site last May closed access for five hours and campaigners staged a 24-hour rooftop occupation in September.