Security protocols failed in preventing a major jewellery heist at the Louvre museum in Paris, leaving the country with a terrible image, France's justice minister has said.


Thieves wielding power tools broke into the world's most-visited museum in broad daylight on Sunday, stealing eight items described as of inestimable value, before escaping on scooters.


Security measures have been tightened around France's cultural institutions, advisers for the country's interior minister said.


There are fears that, unless the thieves are caught quickly, the priceless items, including a diamond and emerald necklace Emperor Napoleon gave to his wife, will be broken down and smuggled out of the country.


The Louvre announced it would remain closed on Monday while investigations continued.


French media reports that a preliminary assessment by the Court of Auditors (due to be published in November) found that a third of the rooms in the wing where the robbery took place have no surveillance cameras.


What is certain is that we have failed, since people were able to park a furniture hoist in the middle of Paris, get people up it in several minutes to grab priceless jewels, Justice Minister Gérald Darmanin told France Inter radio.


Interior Minister Laurent Nuñez stated that a great vulnerability in museum security was acknowledged, prompting a decision to enhance safety measures post-incident.


The theft, occurring between 09:30 and 09:40 local time, involved masked thieves using a truck equipped with a mechanical lift to access the museum. The robbery lasted only about eight minutes, during which the intruders threatened guards, smashed display cases, and escaped with precious items including the Empress Eugénie's diadem.


In a sobering note, expert Chris Marinello from Art Recovery International emphasized the urgency of the situation, warning that if the culprits are not caught within the next 24 to 48 hours, the stolen jewels may be irretrievably lost.