PARIS - Thieves have made off with a high-priced necklace made by Switzerland's De Grisogono in the second jewellery theft at this year's Cannes Film Festival, the company said on Thursday.

"A necklace was stolen during the Cannes festival and we are working with the authorities," a De Grisogono spokesman said, refusing to comment on the circumstances of the theft or the exact value of the necklace.

This year's Cannes festival has been plagued by a series of thefts, including the spectacular heist last Friday of a million euros ($1.4 million) worth of jewellery from a hotel room occupied by an American employee of Swiss jewellery-maker Chopard.

Police in Nice said the three suspects believed to have broken into the hotel room occupied by an American employee of Swiss jewellery-maker Chopard in the early hours of Friday.

"We presume it was people specialised in this kind of theft," Philippe Frizon of Nice police, who are running the investigation, told AFP.

He said the three suspects entered the room through a door connecting it to an adjoining room while the Chopard employee was out for the evening and removed the small safe containing the jewellery. Among the items taken were necklaces, rings, earrings and bracelets that were to be loaned to stars at the festival.

Police said they were investigating a complaint filed by De Grisogono and that the necklace had gone missing in the resort town of Antibes near Cannes.

France Info radio reported that the missing diamond necklace was worth 1.9 million euros and had been stolen during a gala evening Tuesday at the chic Eden Roc hotel attended by, among others, Paris Hilton and Sharon Stone.

At least two apartments rented by film executives have also been burgled during the festival, with thieves taking cash, jewellery and other personal items.