Oxford University has welcomed new powers to prevent animal rights' extremists holding up work on its research laboratory.

Under the Serious Organised Crime and Police Act, which came into force on Friday, July 1, activists who harass or intimidate anyone involved in the project will face up to five years in prison.

Speak, the organisation set up to protest against the planned £18m animal testing laboratory in South Parks Road, said the legislation would not affect its campaign.

The powers were passed through the Commons before the General Election after the Government pledged to do everything necessary to ensure the building project went ahead. Ministers also promised to compensate the university for financial losses incurred by its struggle with extremists.

Building materials company Travis Perkins pulled out of the project in January 2004 and the university has failed to find another contractor to resume building work since the Montpellier group withdrew last July, claiming workers were being harassed. Extremists will now face criminal charges of "economic sabotage", punishable by up to five years' imprisonment and unlimited fines. Police will have the power to arrest anyone protesting outside individuals' homes. This could result in orders banning them from the vicinity for up to three months.

A university spokesman said: "The university welcomes steps that may assist the police in their efforts to reduce the attacks, harassment and intimidation to which individuals and bodies targeted by animal rights' extremists have been subject.

"I'm afraid we are not able to comment on the contractual arrangements relating to the building and we cannot give a definite date for when building work will recommence, but we hope to resume work on the building in the near future."

Robert Cogswell, spokesman for the Speak campaign, said: "It's difficult to know what to think about this legislation until police charge someone. I don't think it's going to affect the Speak campaign in any way because we don't indulge in harass- ment."

Home Office Minister Paul Goggins added: "These new measures will help to stamp out the abhorrent campaigns of harassment and intimidation that a minority of extremists are engaged in."