Vienna  - A coffin containing the remains of German-born billionaire Friedrich Karl Flick was stolen from his mausoleum in the southern Austrian town of Velden, Austrian news agency APA reported Wednesday.

Police investigators said they thought several criminals were involved in removing the granite slabs weighing several hundred kilogrammes from the grave last weekend.

The motive for the theft was unclear, but unnamed investigators told APA they did not exclude the possibility that the crime was related to extortion.

In 2006, the billionaire with dual Austrian-German citizenship died at the age of 79 in Austria, where he had been living with his wife.

His four children have been reported to have inherited a total of 5 to 6 billion euros (6.4 to 7.6 billion dollars) of the family fortune, which was built by investments in the steel, paper and chemical industries.