Nice, France - An armed robber stole gems worth US$136 million (S$173 million) in a weekend jewelery heist in the French Riviera resort of Cannes, making it the country's biggest gem theft.

The prosecutor's office in the nearby city of Grasse issued the figure on Monday based on an inventory of pieces seized in broad daylight from a precious jewelery exhibition at the luxury Carlton Hotel.

It was well over twice initial estimates, which local media had put at around US$53 million.

The thief burst into the Carlton, on the famed La Croisette seafront, close to midday on Sunday armed with an automatic pistol and with a cap and a scarf concealing his face.

He threatened security guards and sales staff and left moments later with a briefcase containing 72 pieces, including jewels, rings, pendants and diamond-encrusted earrings, from a collection belonging to diamond specialist Leviev.

Just 34 of the stolen items were worth a total of US$135 million, according to the prosecutor's office, which initially valued the loot at "several million euros".

"The man entered by a glass door onto the Croisette which normally should have been bolted," a spokesperson at the prosecutor's office said.

Initial investigations suggested the man may have dropped several jewels as he hurried away on foot via a different door.

The hotel, celebrating its centenary this year, was where Alfred Hitchcock filmed scenes from the 1955 film "To Catch a Thief", starring Cary Grant as a one-time cat burglar and Grace Kelly as the beautiful Frances.

The heist came two months after two smaller jewelery robberies hit the annual Cannes film festival, where movie stars are lent gowns and gems to parade on the red carpets.

It was the biggest theft of jewels on record in France.

A group of men disguised as women shoppers pulled out guns and made off with around US$105 million worth of jewels from the Harry Winston jewelery store on the Avenue Montaigne in Paris in 2008.

Photos: AFP, Reuters

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