Notre-Dame's famed stained-glass rose windows and most of its many religious relics appeared to have escaped the worst of Monday's inferno as well, easing fears for the fate of the vast trove of artworks in the 800-year-old gothic cathedral.

Among the most cherished articles to make it out unscathed was the "Sainte Couronne" (holy crown), made of braided reed brought to France from Constantinople in the 12th century. Though lacking its original thorns, the crown has been revered as an object of Christian worship for centuries.

Gold, silver and gem-inlaid chalices, candelabras and many other artefacts survived the blaze thanks to quick-thinking firefighters, police and city employees who formed a human chain to move revered artefacts away from the flames.

Paris Mayor Anne Hidalgo tweeted a picture of heavy-set candlesticks stacked in the safety of nearby Paris City Hall.

Art specialists were still poring over the extent of the damage to Notre-Dame's 13th-century South Rose Window, measuring 10 metres across, and other stained-glass masterpieces still standing after the cathedral's wood-beamed roof collapsed.

"It seems they have not been destroyed for now, although we'll have to see what real state they're in, and whether they can be restored properly," said Maxime Cumunel, secretary general of France's Observatory for Religious Heritage.

"We have avoided a complete disaster. But some five to 10 per cent of the artwork has probably been destroyed, we have to face up to that," Cumunel said.

Four of the largest-scale 17th and 18th century paintings depicting scenes from the lives of the apostles had been damaged, at least in part, he added.

Culture Minister Franck Riester said the paintings were mainly affected by smoke damage, rather than by flames.

The artworks, which were dampened during the 15-hour battle to douse the blaze, will be removed from Friday and transferred to the Louvre museum, where other objects will also be kept, for attempts at restoration, he added.

It remained unclear how well the cathedral's towering master organ, embedded into a sculpted wooden casing, had fared, as rescuers remained on high alert for the possibility that some of Notre-Dame's fragile vaults might come crashing down.

The organ - which survived the French Revolution in the late 18th century, when it was used for recitals of patriotic songs - may have been slightly damaged too, according to Cumunel, though city hall officials said it was largely intact.

Most of the sacramental artefacts in Notre-Dame's treasury - where they were traditionally kept as reserves to be sold off or melted down in times of need - date from the 19th and 20th centuries.

Other relics that made it out of the wreckage included a tunic worn by Saint Louis, a 13th-century king of France, while the cathedral's 13-tonne bell, its largest, which rings sonorously on special occasions like Easter, was spared.

Sixteen bronze statues that adorned Notre-Dame's collapsed spire - itself a 19th-century restoration - were airlifted out just days before the fire as part of ongoing renovations.

A gold cross stood eerily intact above the altar on Tuesday, surrounded by debris - the first images from inside the cathedral that reached the wider world.

Australian Associated Press