Six animals rights activists who targeted companies linked to Huntingdon Life Sciences in an attempt to close down the animal testing lab will appear in court today at the start of their sentencing hearing.

Sarah Whitehead, 53, Nicole Vosper, 22, Thomas Harris, 27, Jason Mullan, 32, Nicola Tapping, 29, and Alfie Fitzpatrick, 20, were all members of Stop Huntingdon Animal Cruelty SHAC.

The Recorder of Winchester, Judge Keith Cutler, will sentence the six during the two-day hearing at Winchester Crown Court.

The gang waged an international campaign of intimidation over a seven-year period against a host of supply companies to force the closure of HLS.

Homes of staff and offices were targeted with hoax bomb threats, criminal damage and abusive telephone calls. Threats of violence were also used to force companies to cut links with HLS.

Some company directors had leaflets distributed near their home falsely telling neighbours they were paedophiles and others had used tampons sent through the post saying the blood was HIV positive.

The abuse would only stop when the company issued a capitulation statement and cut links with the lab.

Whitehead from Thorncroft Road, Littlehampton, West Sussex, Vosper from Bay View Terrace, Newquay, Cornwall, and Harris from Clarence Road, Gosport, Hampshire, have admitted conspiracy to blackmail companies and suppliers linked to the Cambridge-based company between 2001 and 2008.

Mullan from Holloway Road, London, Tapping from Clarence Road, Gosport, and Fitzpatrick from Knowle Road, Solihull, West Midlands, all pleaded guilty to conspiracy to harm Huntingdon Life Sciences from 2005 to 2008 under the Serious Organised Crime and Police Act 2005 by interfering with companies supplying them.

The maximum jail term for conspiracy to blackmail is 14 years and for conspiracy under the Serious Organised Crime and Police Act 2005 is five years.

Other members of SHAC, including the founder members Gregg Avery, Natasha Avery and Heather Nicholson were jailed in January 2009 at Winchester Crown Court for blackmailing companies linked to HLS.