Louvre detectives believe £76m jewellery heist was an 'inside job'

Fleeing with the historical artefacts as part of the broad daylight raid, questions were instantly raised over the group's knowledge of the building - including targeting a location not covered by security cameras and knowing the external window alarms were not armed.

Making off in just seven minutes and fleeing on mopeds after returning to street level, the jewels have not been seen since, amid concerns they may have already been broken down and sold.

Detectives investigating the case have now revealed their suspicions that the heist was, as many suspected, an inside job.

A source told the Telegraph: “There is digital forensic evidence that shows there was cooperation with one of the museum’s security guards and the thieves.

According to French detectives, police now have evidence that "a member of museum security team was in contact with" suspected thieves.

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“Sensitive information was passed on about the museum’s security which is how they were aware of the breach,” the source added.

With the thieves yet to be formally identified, the source added that current evidence includes recordings and text messages.

Video footage emerged earlier in the week of the gang slowly descending from the internationally renowned gallery on a cherry picker in broad daylight.

Harnessing the worldwide attention, the lift's manufacturer put out a tongue-in-cheek advert suggesting their equipment had other uses.

In the footage, passers-by can be seen walking beside the River Seine.

Further footage shot by Louvre visitors shows the men targeting the museum's glass cases with chainsaws.

The video footage was reportedly taken on a security guard’s mobile phone.

The video shows one of the gang already in motorbike gear including a helmet ready to ride off.

In further embarrassment for French officials, it emerged today that none of the crown jewels stolen from the Louvre were covered by insurance because the premiums on the 'priceless goods' were too high.

The eight items, worth an estimated €88m (£76m), were stolen from cabinets in the Paris museum on Sunday by a gang of power-tool wielding thieves.

French police are racing to track down the gang behind the audacious heist, but experts fear the stolen crown jewels, once worn by Napoleon’s wife, may already be lost forever.

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It has now been revealed that France will not receive any payout from the heist, as the precious jewels were nearly impossible for insurers to appraise.

Similar to many public museums, the Louvre is self-insured and absorbs any costs related to loss, theft and damage.

A spokesman for the museum said: “The state acts as its own insurer when national museums’ works are in their typical place of conservation.”

The ministry of culture added that the insurance premiums for the pieces would be astronomical, as the Lourve holds tens of thousands of works and is unlikely to sell its masterpieces.

Insurance is normally only acquired for these items when they are being transported between other museums.

The Crown Jewels of the UK – which include “priceless” artefacts such as the Coronation Regalia, sceptres, swords and rings – are also not insured.

The theft has sparked anger and soul-searching over how France protects its most prized treasures.

As a result, the Louvre’s president Laurence des Cars submitted her resignation, which was rejected by Emmanuel Macron.

The heist has raised fresh questions about how well France protects its cultural treasures.

The Louvre is the world’s most-visited museum, welcoming more than eight million people a year – yet experts say its defences lag behind newer institutions.

But culture minister Rachida Dati said there were no faults in the museum's security during the multi-million-pound heist.

"The Louvre museum’s security apparatus did not fail, that is a fact,” she told France’s National Assembly on Tuesday.

Ms Dati said questions should now turn to the policing of the nearby roads and how the thieves were able to enter through a window using an extendable ladder mounted on a truck.

"Perhaps we should be asking ourselves questions, and this is something we are discussing with the minister of the interior, but also with the Paris City Hall, about public highway security, which did not exist at this stage,” she said.

Experts have warned the items have likely already been broken down and sold off piece by piece on the black market.

If the jewels are broke up or melted down for gold, they will not be worth the equivalent of the original valuation put on them by the museum’s curator.

Thieves smashed their way into the Galerie d’Apollon, home to France’s crown jewels, on Sunday morning and escaped within eight minutes with the pieces.

The stolen items included a tiara, necklace and earring from the sapphire set of Queen Marie-Amelie and Queen Hortense.

The robbers also stole an emerald necklace, a pair of emerald earrings and a brooch known as the "reliquary brooch" from the Empress Marie Louise set, as well as the tiara and a large corsage bow of Empress Eugenie.

A ninth piece, the crown of Empress Eugénie, was broken during their escape and has now been retrieved.

Experts say the treasures’ historical value is beyond measure, and their fame makes them almost impossible to sell intact.

Crime-heritage Professor Marc Balcells said: “If I steal a Van Gogh, it’s a Van Gogh … But when I am stealing … jewellery, I can move it through an illicit market as precious stones.”

The museum re-opened on Wednesday, three days after the brazen robbery, with visitors welcomed back on the premises at 9am.

But the Apollo Gallery - where the heist took place - remains closed.

Police are still analysing CCTV footage and mobile data from around the museum and neighbouring streets. Interpol has been alerted in case the jewels are moved abroad.

But veteran investigators say even if arrests are made, the chances of finding the original pieces are slim.

Christopher Marinello, founder of Art Recovery International, which tracks stolen art, warned that “once they’ve been cut into smaller jewels, the deed is done… We’ll never see these pieces again intact.”