PARIS - ARMED robbers pulled off one of the world's biggest jewellery heists at a famed Paris store, making off with diamonds and valuables worth 80 million euros (S$154 million dollars), investigators said Friday.

The four robbers on Thursday stole nearly all the jewellery on display at Harry Winston jewellers on the Avenue Montaigne, which attracts a wealthy international clientele just off the Champs-Elysees.

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 jewels.

Two of the four men were disguised as women when they managed to elude the high-security surveillance system and burst into the boutique at 5.30pm (12.30am, Friday, Singapore time) on Thursday during the busy holiday shopping season.

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

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

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.

Police on Friday were questioning customers, employees and pedestrians to try to come up with clues.

Harry Winston, which specialises 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 US$500,000 (S$761,390) reward for information leading to the thieves' arrest but they were never found.

The US jewellery chain has stores across the world and 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.

Belgium holds the record for the world's biggest jewellery heist when diamonds worth 100 million euros or more were stolen on February 14, 2003 in Antwerp.

A 1.8 million euro necklace was stolen in June 2001 from the Alexandre Reza shop in Cannes on the French Riviera, followed a month later by a 3.8 million euro heist at a Van Cleef and Arpels shop in the same city.

Among other notable heists, three Paris shops were targeted in October 2001 by a conman posing as a rich Kuwaiti emir who managed to make off with 2.2 million euros in jewels. -- AFP