An animal rights activist has been jailed for sending threatening letters.

Janet Lawrence, 51, the ex-wife of a high-ranking Army officer, targeted people and businesses who had links with animal testing organisations.

Some of her terrified victims lived or worked in Sussex. They were left fearful after receiving the hate mail through the post to their homes or businesses.

The scared victims increased security in their homes. One family bought a guard dog and another hired a private security firm.

The letters, all written in red ink, contained aggressive tirades and warned the recipient was a legitimate target of the Animal Liberation Front.

One letter sent to a person in Sussex said: "You profit from animal cruelty at Huntington Life Sciences. You are a sick, evil, perverted deviant. You are now a legitimate and priority ALF target. The animal rights militia exists just for filthy, animal-abusing scum like you.

"Dump HLS now. You have been warned."

Lawrence, a mother-of-one, of Sunbury, Middlesex, showed no emotion as she was sentenced to eight months in jail at Lewes Crown Court.

She admitted one charge of causing a public nuisance and asked for ten similar offences to be taken into consideration. She denied 18 charges of blackmail and these were ordered to remain on the court file.

Judge Richard Hayward also imposed an antisocial behaviour order banning her for five years from going within one mile of Huntington Life Sciences, in Cambridgeshire, which carries out research involving animal testing for the pharmaceutical industry.

She is also banned from communicating with anyone involved with or linked to the firm and Oxford University.

Greg Perrins, prosecuting, told the court Lawrence sent 18 anonymous letters between May 2003 and November last year to the businesses and homes of her victims.

He said the recipients were members of the public believed by her to have a connection with Huntington Life Sciences.