A company supplying industrial washing machines to hospitals and laboratories was forced to stop trading with an animal research centre after employees’ families were threatened by animal rights activists, a jury has heard.

Supporters of the Stop Huntingdon Animal Cruelty (SHAC) group conducted “noisy” demonstrations outside Lancer UK Ltd’s offices and sent staff emails and letters between July and December 2006 to get them to stop doing business with Huntingdon Life Sciences (HLS), Winchester Crown Court was told on Wednesday.

In December 2006 two employees received letters saying members of their family could be attacked if the links between the two Cambridgeshire-based organisations were not severed, the court heard.

The prosecution said the members of staff were targeted because their firm had supplied HLS, an animal-testing laboratory, with a washing machine.

The statement of one of the victims, who cannot be named, was read out at the trial of five alleged SHAC activists charged with conspiracy to blackmail.

Heather Nicholson, of Pond Croft in Yateley, Gerrah Selby, formerly of Aldershot Road, Church Crookham, Daniel Wadham, formerly of Pond Croft, Yateley, Gavin Medd-Hall, from Croydon, and Trevor Holmes, from Crawley, West Sussex, deny conspiring between November 15, 2001 and May 2, 2007, to blackmail those companies they believed to be associates of HLS.

During the trial the prosecution told the court that SHAC’s sole aim is to shut down HLS.

The court heard SHAC, under the badge of Animal Liberation Front (ALF) or the Animal Rights Militia, would blackmail companies it believed to be associated with HLS.

Those companies would then be subject to “direct action” which could include protests, threatening emails and criminal damage, until they released a “capitulation statement” saying they would stop working with HLS, the prosecution said.

On Wednesday, the jury was shown a picture of the letters sent to the Lancer UK employees which said: “You’ve had your chance to sever links with HLS. We are giving you seven days to stop doing business with them for good or you will face the consequences.

“We will attack your property, your family or you. Anything goes. If you do not see sense you will only have yourself to blame. We will make you suffer.”

In a statement read out by pro-secutor Stephen Climie, one employee said the “direct threats” against his family had caused his wife “considerable stress”.

The court heard that due to the threats Lancer UK’s contract with HLS was terminated. The company sent an email to SHAC confirming it, the prosecution said.

The trial continues.