Animal rights activists on Thursday claimed responsibility for starting a huge fire at the Austrian holiday home of Novartis head Daniel Vasella and warned of further attacks.

The organisation demanded the Swiss drug company cut ties with Huntingdon Life Sciences, the controversial British animal-testing laboratory, and warned Vasella: "We will destroy your life."

"It hasn't been your week has it, Daniel?" said the Militant Forces Against Huntingdon Life Science Austria in a statement posted on the Internet.

"Understand this: this will continue until you sever all ties with Huntingdon Life Sciences.

"We will attack your private life wherever possible."

The Austrian interior ministry said it not heard of the group before and Novartis had earlier blamed the arson on a different organisation.

An interior ministry spokesman added the authenticity of the claim was being checked.

The animal rights campaigners revealed in the statement that the house was doused with 60 litres of petrol bombs were placed in and around the house.

A picture of the fire-gutted building was also posted on the Internet along with the statement.

The blaze at the chief executive's holiday home in the small Tyrolean village of Bach was discovered in the early hours of Tuesday by a German holidaymaker, and it took around 100 firefighters to extinguish the blaze.

Nobody was injured, police said, and Vasella was not at the villa at the time of the fire.

The blaze came after the tomb of Vasella's mother was desecrated in the eastern Swiss town of Chur in July.

Novartis said Tuesday they had "no doubt" another group, the Stop Huntingdon Animal Cruelty (SHAC), was behind the arson.

Although it has carried out a string of attacks on Novartis in the past, the SHAC denied involvement in the latest incident.

The group, which campaigns against animal testing, is believed to have been behind the desecration of Vasella's mother's tomb last week.

Animal testing laboratory Huntingdon Life Sciences, in eastern Britain, provides testing services to a wide variety of firms, including the pharmaceutical and chemical industries.

The company became a focal point for anti-vivisection extremists and has long been the target of attacks.