Vienna - Animal rights activists have claimed responsibility for burning down an Austrian house of the chief of pharmaceutical giant Novartis, triggering an investigation by Austria's anti- terrorism agency, police confirmed Thursday.

The fire at Daniel Vasella's hunting lodge on Monday was the latest in a string of attacks against the Swiss-based company, including the theft of the ashes of Vasella's mother in late July.

A group called Militant Forces against Huntigdon (MFAH) Austria posted a message on a US website, claiming it started the blaze because of Novartis' alleged cooperation a with British company conducting tests on animals.

"It hasn't been your week has it, Daniel?," MFAH wrote on the site www. directaction. info, "This will continue until you severe all ties with Huntingdon Life Sciences."

Novartis does not make its cooperation partners public.

Austria's police intelligence service, which is also involved in anti-terrorism work, has taken over the investigation, Austrian press agency APA reported.

The activists claimed they placed 60 litres of petrol around the house, which was part of Vasella's hunting estate in the Tyrol mountains.

In Switzerland, Novartis employees and facilities have been targeted by animal rights extremists in recent months. Swiss media have reported that a group called Stop Huntigdon Animal Cruelty was likely behind those attacks. (dpa)