Paris police confirmed on Sunday that they were suspected of breaking into the most visited art gallery in the world a week ago.

The men were under surveillance after forensic evidence pointed to them being around the Louvre last Sunday, said the investigating source.

This is common practice after a heist, as police hope suspects will lead them to the stolen goods.

When one of the men was seen at the airport, however, detectives took the 'emergency decision' to make the arrests.

The men were taken to the high-security headquarters of the Paris judicial police, where they were being questioned on Sunday.

Referring to a suburb north of the French capital, an investigating source said: 'They are in their 30s, and come from Seine St Denis.

'One was arrested at Charles de Gaulle airport, as he attempted to take a flight to Algeria on Saturday night, at about 10pm.'

The two men, already known to the police for burglaries, have the profile of seasoned burglars who may have being acting to order.

The Louvre burglars left at least 150 DNA samples including fingerprints behind before they fled.

Details of the evidence against the four raiders were revealed by the Paris prosecutor who remained 'optimistic' that they would soon be found.

Laure Beccuau was speaking after the spectacular broad daylight heist on the most visited art museum in the world.

She hoped that the criminals had previous convictions, meaning their DNA would already be on forensic data bases, and could be matched.

'Analysis requires time, and is of course a priority for the laboratories,' said Ms Beccuau.

'Work in the coming days may open up leads, especially if the perpetrators are on file.'

The '150 trace samples' were left on a stolen flatbed truck, and on a crash helmet and glove that were abandoned.

There were attempts to set the vehicle on fire, but they failed, as the raiders got away on two motorbikes following a burglary that lasted just seven minutes.

Four raiders were seen at the Louvre last Sunday, and some were videoed by witnesses.

The jewellery taken included a broach containing 2348 diamonds, and a tiara with 1083 diamonds - all of it once worn by relatives of Napoléon Bonaparte.

Five security guards ran away, while police responding to an alarm arrived far too late to see the gang disappearing on two motor scooters.