Protests outside the homes of scientists who experiment on animals and the harassment of anyone associated with their laboratories will be dealt with under measures announced by the government yesterday.

The interdepartmental initiative, subtitled "protecting people from animal rights extremists", rejects calls for a new parliamentary act to combat militant anti-vivisectionists. But their websites will be watched and those maliciously ordering goods and services by post in someone else's name will be pursued.

Shareholders in companies involved in animal research will be encouraged to disguise their home addresses, being reminded that there is no legal obligation to give addresses in public registers.

The hastily assembled programme was released in response to the success of direct action in stopping work on a new laboratory for Oxford University and forcing the main contractor, Montpellier, to abandon the project earlier this month. No other company has taken on the contract.

The Home Office dismissed speculation that troops might be used to counter harassment campaigns. "We have no plans to send the army in," a spokesman insisted.

The 20-page document, with a foreword signed jointly by the prime minister and the home secretary, defends the use of animals in scientific research, outlines attempts to develop medical alternatives, and concentrates on sharpening the existing array of law and order tools to defeat the "extremists".

Three new offences are proposed to give the police power "to tackle protests outside homes more effectively" and prevent the harassment of employees of companies involved in the industry.

Officers should be able to arrest anyone demonstrating outside a house "in such a way that causes harassment, alarm or distress to residents".

A new offence created by amending section 42 of the Criminal Justice and Police Act 2001 would forbid those "moved on" from returning to a house within three months for "the purpose of representing to or persuading the resident, or anyone else, that he should not do something he is entitled to do, or that he should do something he is not obliged to do".

Expansion of the 1997 Harassment Act would make it easier to arrest someone for harassing as few as two employees of a company, "even if each individual is harassed on only one occasion".

The paper says the government has not closed on door a new law dealing solely with crimes by animal rights extremists, but adds: "It would not be sensible to try to seek a separate bill which, because of pressures of parliamentary time, could not be taken this year".

Because anti-vivisections target the research laboratories' commercial lines of supply, the government considered creating an offence of causing "economic damage", but admits that it has made little progress in "a complex area which is difficult to define".

Websites detailing acts of sabotage by such groups as the Animal Liberation Front will be addressed, even if based abroad.

"We will coordinate legislation, policy and action by industry, the police, [prosecutors] and others," the paper says, "to deal effectively with the hosting of material on animal extremist websites, in particular [those which publish] personal details of individuals and companies at risk of being targeted by extremists."

Harassment has frequently taken the form of ordering material, often pornographic, through the mail in the name of those targeted. The government says it will review the laws governing such activities to find the most effective way of stopping it.

The government also asks people to be careful not to give money to "extremists".

"Such well-intentioned donations are unlikely to help animals but are far more likely to be funding criminal activity," the paper says. "Sometimes well-meaning people give money to stalls in high streets and shopping centres without knowing exactly what the money will be used for."

The Home Office minister Caroline Flint said: "By toughening up the law on protests and harassment, and with robust enforcement by the police and courts, the government intends to put a stop to the animal extremists' reign of terror.

"It is wholly unacceptable that a small number of criminal extremists attempt to stop individuals and companies going about their legitimate business."