Security at the luxury Carlton hotel in the French Riviera town of Cannes is under the spotlight in an investigation into a jewel heist at the weekend worth €103 million ($136 million), police sources said on Tuesday.
"At the very least, the managers were a little careless," said a police source, adding that the security system in place at the Carlton - a hotel popular with film stars - was "a bit out of date".
Police said they had not been alerted that the "Extraordinary Diamonds" exhibition, put on by a group owned by Israeli billionaire Lev Leviev, was taking place.
The exhibit was held in a wing of the hotel with direct access to the street.
According to a source close to the case, the jewellery house Leviev was using its own security guards for the exhibition.
While not a legal requirement, alerting the police would ordinarily be standard procedure for luxury hotels such as the Carlton.
"For three years now, the Carlton has not informed us when it puts on this kind of event," said the police source.
Hotel management used to oversee security but in recent months the task had fallen to a single manager who was previously responsible for purchasing and laundry, said police. "He has training but that doesn't make him a security professional," said the source.
The Carlton has denied all responsibility for the heist.
Its director, Francois Chopinet, told AFP in an email that "no client at the hotel or staff" was implicated in the incident.
InterContinental Hotels Group, to which the Cannes hotel belongs, was not available for comment.
Hotel employees and unions at the hotel have laid the blame firmly with the Carlton.
According to union member Ange Romiti, the security in the room was "not suitable" for the exhibition.
The heist took place on Sunday when a man armed with a semi-automatic pistol walked into the hotel, then proceeded to steal the jewels.
The thief escaped with 72 pieces including rings, necklaces and bracelets, including 34 "exceptional" pieces.
According to a source close to the investigation, the man was "well informed, because he acted at the right moment, in the right place".
Seconds later, the thief fled through a French window which looks out onto the famous Croisette promenade popular with tourists, dropping several pieces of "lesser value" on the way.
While the particularly bling pieces that were stolen, worth millions of euros each, were insured, the other jewels - worth between €20,000 and €40,000 - were not, a source close to the investigation said.
Leviev's insurance should cover all of the lost pieces, Jacques Lemoine, an industry specialist, told AFP, adding that the British bank Lloyds had acted as insurers for Leviev.
The heist comes head-to-head with what is considered the world's largest ever haul of jewellery - valued at around €100 million - which took place in Belgium in 2003.
It is also France's biggest jewellery heist.
The CGT union said Monday that the Carlton had already been the victim of a jewellery heist in 1994, when a security guard was seriously wounded by a bullet.