Around 50 firemen put out the blazes which broke out within 40 minutes of each other at the restaurants in Avrainville, Villejust and Ville du Bois.

Two of the establishments were completely gutted.

The company's president Francois Picart said the fires "could only be criminal".

"It couldn't be robberies that were covered up," he told AFP.

The company called on the authorities to provide protection for their chain of 260 restaurants as the fires were a "criminal act with the intention to destroy."

Late last year trading of shares in the Buffalo Grill chain was suspended for three weeks owing to a scandal over alleged secret imports and use of banned British beef.

Trading was suspended on December 18 amid allegations the company illegally imported British beef and served it to customers at a time when it was banned due to fears of "mad cow" disease.

French authorities launched criminal investigations against several of the group's senior executives in December after finding that two people who died of Creutzfeldt-Jakob disease -- the human variant of mad cow disease -- had eaten at Buffalo Grill outlets.

Investigators were still studying what caused the fire at Villejust, where the blaze was quickly brought under control.

Fire damaged video surveillance tapes at two of the restaurants, police said, but they will be sent to experts to try to retreive images.

SPACE.WIRE