A package of measures to protect scientists involved in animal experimentation from the protests of "animal rights extremists" has been announced by the home secretary.

The plans include amendments to the Criminal Justice and Police Bill, currently going through parliament, which would give the police new powers to prevent or move protests outside people's homes Sending of hate mail, including emails and text-messages, would also become an imprisonable offence.

"We simply will not tolerate the criminal actions of a small number of extremists who use violence and intimidation to stop people going about their legitimate business," Jack Straw said.

The government also plans to issue guidance to shareholders and employees who may become targets, outlining steps they can take to improve their personal security and avoid unnecessary publication of their home addresses.

"This type of [animal] research saves lives and treats the illnesses of millions of people - the people conducting it must be able to go about their work free from the fear of violence or intimidation," said Straw.

He added: "Peaceful public protest is entirely legitimate, but there is a world of difference between that and the type of intimidation, threats and violence we have seen recently."

In a statement Michelle Thew, the chief executive of the British Union for the Abolition of Vivisection, condemned the use of threats and intimidation but added that "we are also concerned that any legislative measures taken by the government should not curtail the right of legitimate protest."

She also urged the government to look at the reasons for the recent protests against laboratories such as Huntingdon Life Sciences and noted that "Simply increasing police powers will not solve the problem. The government's record on lab animals is very poor."

"There is no need to reveal the identity of researchers, simply details about the experiments and their alleged purpose. Only a proper public debate can take the heat out of the situation," she concluded.