PARIS (AFP) Armed robbers pulled off one of the world's biggest jewelery heists at a famed Paris store, making off with 80 million euros (102 million dollars) in diamonds and valuables, investigators said Friday.

A gang of four thieves -- two of them disguised as women -- on Thursday stole nearly all the jewels on display at the Harry Winston boutique just off the Champs-Elysees avenue, which attracts a wealthy international clientele.

The heist was well-planned, a source from the investigating team told AFP. The men knew the names of some of the shop's employees and the location of some hidden storage cases for jewellery.

The robbers managed to elude the high-security surveillance system and burst into the boutique at 5:30 pm (1630 GMT), at the height of the holiday shopping season.

Brandishing weapons, they threatened some of the dozen employees and customers and herded them into a corner, while some of the staff suffered blows, according to investigators.

The loot initially estimated at up 62 million euros was revised early Friday to 80 million euros, making it by far the biggest jewellery heist yet in France.

Police said they were dealing with "major pros" who had meticulously planned their crime and knew the boutique's lay-out well, suggesting it may have been an inside job.

The thieves, who apparently were French-speaking, stuffed brooches, rings, necklaces and other finery in bags and quickly left, without firing a shot. The whole operation lasted just 15 minutes.

No leads were ruled out including the possibility that the robbers may have connections in eastern Europe, where the loot could be sold, contrary to western Europe where such high-value stolen goods would be quickly detected.

Police described the eastern European market as a "new El Dorado for traffickers" trying to get rid of high-end stolen goods.

Investigators were Friday questioning customers, employees and pedestrians and studying surveillance camera tapes for clues, while Harry Winston's head branch in New York said it was working closely with the French authorities.

"We are cooperating with the authorities in their investigation. Our first concern is the well-being of our employees," the company said in a statement.

The Harry Winston store on Avenue Montaigne, which specializes in ultra-luxury jewellery, was hit by another heist in October last year when armed robbers stole an estimated 10 million euros worth of valuables.

An insurance company offered a 500,000-dollar reward for information leading to the thieves' arrest but they were never found.

The US jewelery chain has sold precious stones to royal families and lent them to film stars for events such as the Cannes film festival or the Oscars in Hollywood.