The six were all member of a group called Stop Huntingdon Animal Cruelty (SHAC) Five animal rights activists have been jailed for intimidating staff at firms linked to a Cambridgeshire animal testing laboratory.
Nicole Vosper, Sarah Whitehead, Thomas Harris, Nicola Tapping and Jason Mullan were jailed for between 15 months and six years.
They admitted targeting staff from the supply firms of Huntingdon Life Sciences, Winchester Crown Court heard.
Alfie Fitzpatrick, 21, received a 12-month suspended prison sentence.
He also admitted taking part and was ordered to complete 100 hours of community work.
Harris and Tapping are from Gosport in Hampshire while Jason Mullen is from London and Fitzpatrick from Solihull, West Midlands.
Vosper is from Newquay in Cornwall and and Whitehead is from Littlehampton, West Sussex.
The six were all members of a group called Stop Huntingdon Animal Cruelty (SHAC).
The court heard how the group waged an international campaign of intimidation against a host of companies to try to force the closure of Huntingdon Life Sciences (HLS).
Homes of staff from the supply firms were targeted with abusive telephone calls while criminal damage and threats of violence were also used to force companies to cut links with HLS.
Realistic hoax bombs were posted to the homes of staff and to offices.
Some company directors had leaflets distributed near their homes falsely telling neighbours they were convicted paedophiles and others had used tampons sent through the post saying the blood was HIV positive.
Whitehead, 53, of Thorncroft Road, was jailed for six years and made the subject of a 10-year anti-social behaviour order when released.
Vosper, 22, was jailed for three-and-a-half years and given a five-year anti-social behaviour order.
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