French President Emmanuel Macron has vowed to rebuild Paris’s Notre Dame Cathedral, as investigators in Paris praise a human chain of rescue workers for saving many priceless artefacts from the church.

Mr Macron declared in a televised address on Wednesday morning (AEST) that the 800-year-old national landmark will be restored within the next five years.

“We will rebuild Notre Dame even more beautiful and I want that to be done in the next five years,” he said.

But at least one expert claims the full restoration could take “10 to 15 years”.

Frédéric Létoffé, the head of the group of companies for the Restoration of Historic Monuments, told media in Paris that the site would need to be secured before any restoration work can take place.

“This will require a lot of work since, beyond shoring and reinforcement, it will be necessary to build a scaffolding with an umbrella to be able to cover the entire roof that went missing, to ensure protection against weathering” Mr Létoffé said.

The catastrophic fire that devastated large parts of the famed Cathedral on Tuesday morning (Australian time) is believed to have been accidental and possibly linked to the recent renovations of the cathedral spire.

Minutes after the fire began threatening religious relics, a human chain took shape to salvage as many sacred items as possible.

“We made a human chain, with our friends from the church … to get, as quick as possible, to get all the relics,” Paris’ deputy mayor for tourism and sports, Jean-Francois Martins, told CBS This Morning.

France’s deputy interior minister Laurent Nuñez said there was a crucial 15-30 minute period where firefighters managed to prevent more damage to the structure.

Firefighters were first on the scene, grabbing whatever they could and carrying it to safety.

Not long after, they joined Parisian officials and church caretakers, including Reverend Jean-Marc Fournier and the chaplain of the Paris fire brigade, who had already begun forming the human chain.

Due to their quick-thinking, most religious relics including Notre Dame’s famed stained-glass rose windows, gem-studded chalices and candelabras appeared to have escaped the worst of Tuesday’s inferno.

The Crown of Thorns relic saved from the fire. Photo: Getty

Among the most cherished articles to make it out unscathed was the Sainte Couronne (holy crown), followers believe was worn by Jesus before his crucifixion

Though lacking its original thorns, the crown has been revered as an object of Christian worship for centuries. 

Paris deputy mayor Emmanuel Gregoire described authorities’ “enormous relief” at the salvaging of pieces such as the purported Crown of Christ, which were being transported to a “secret location” after the fire.

The mayor of Paris, Anne Hidalgo, tweeted her thanks to “firefighters, police and municipal agents” for forming the “formidable human chain” to save major works.

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

L’Hotel de Ville a accueilli des tableaux, des candélabres et des objets précieux,sauvés de l’incendie,avant de rejoindre des structures plus adaptées à la conservation de ce patrimoine.Belle mobilisation du #servicepublic dans son ensemble pour sauver tout ce qui est #notredame pic.twitter.com/bUCOCIabcF

— Christophe Girard (@cgirard) April 16, 2019

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.

Les agents du @MinistereCC, épaulés par les équipes de l’archevêché, les @PompiersParis et les forces de sécurité, évacuent les œuvres se trouvant à l’intérieur de la cathédrale. Elles sont progressivement mises en sécurité. #NotreDame pic.twitter.com/iINHyUqJME

— Franck Riester (@franckriester) April 15, 2019

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.

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 (local time), surrounded by debris – the first images from inside the cathedral that reached the wider world.

-with AAP