Security measures will be tightened around France's cultural institutions after a major jewellery heist at the Louvre museum in Paris on Sunday, advisers for the country's interior minister have said.

The decision was made on Monday after a meeting with police and ministers, including Interior Minister Laurent Nuñez.

It comes after the justice minister said security protocols "failed" in preventing the heist, giving France a "terrible image".

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

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 up and smuggled out of the country.

The museum announced it would be staying closed on Monday while investigations continued.

French media report that a preliminary assessment by the Court of Auditors (due to be published in November) said 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, giving France a terrible image," Justice Minister Gérald Darmanin told France Inter radio.

He added that he was certain police would eventually arrest the thieves.

But the head of an organisation specialising in the location and recovery of stolen artworks warned that if the thieves are not caught in the next 24 to 48 hours, the stolen jewellery will likely be "long gone".

"There is a race going on right now," Chris Marinello, the chief executive of Art Recovery International, told BBC World Service's Newshour programme.

Crowns and diadems - which were stolen in the heist - can easily be broken apart and sold in small parts.

The thieves "are not going to keep them intact, they are going to break them up, melt down the valuable metal, recut the valuable stones and hide evidence of their crime," Mr Marinello said, adding it would be difficult to sell these jewels intact.

The French police "know that in the next 24 or 48 hours, if these thieves are not caught, those pieces are probably long gone," he said.

"They may catch the criminals but they won't recover the jewels."

Nuñez said he was aware of "a great vulnerability" in museum security in France.

President Emmanuel Macron described the robbery as an "attack on a heritage that we cherish because it is our history".

And Nathalie Goulet, a member of the French Senate's finance committee, told the BBC it was a "very painful" episode for France.

"We are all disappointed and angry," she said, and it is "difficult to understand how it happened so easily."

Goulet told BBC Radio 4's Today programme that the gallery's alarm was recently broken, and "we have to wait for the investigation in order to know if the alarm was disactivated."

She said the cut up jewels would be "used in a money laundering system."

"I don't think we are facing amateurs. This is organised crime and they have absolutely no morals. They don't appreciate jewellery as a piece of history, only as a way to clean their dirty money," she added.

The theft took place between 09:30 and 09:40 local time on Sunday morning, shortly after the museum opened to visitors.

Four masked thieves used a truck equipped with a mechanical lift to gain access to the Galerie d'Apollon (Gallery of Apollo) via a balcony close to the River Seine.

Pictures from the scene showed a vehicle-mounted ladder leading up to a first-floor window.

Two of the thieves cut through glass panes with a battery-powered disc cutter and entered the museum.

They then threatened the guards, who evacuated the building.

The thieves smashed the glass display cases and stole the jewels, which collectively contained thousands of diamonds and precious gemstones.

The robbery took just seven minutes.

As the museum's alarms started blaring, staff followed protocol by contacting security forces, the culture ministry said in a statement.

The thieves had tried to set fire to their vehicle outside but were prevented by the intervention of a museum staff-member, it added.

Eight items of jewellery were stolen in total, including an emerald and diamond necklace that Napoleon gave his wife, Empress Marie Louise.

Also taken was a diadem (jewelled headband) that once belonged to the Empress Eugénie - wife of Napoleon III - which has nearly 2,000 diamonds.

They also took a necklace that once belonged to Marie-Amelie, the last queen of France, and which contains eight sapphires and 631 diamonds, according to the Louvre's website.