Flames on the roof of the Notre-Dame Cathedral in Paris, France, 15 April 2019. Picture: EPA/IAN LANGSDON

Smoke is seen around the alter inside Notre Dame cathedral in Paris, Monday, April 15, 2019. (Philippe Wojazer/Pool via AP)

Flames and smoke are seen billowing from the roof at Notre-Dame Cathedral in Paris on April 15, 2019. (Photo by LUDOVIC MARIN / AFP)

Flames and smoke are seen billowing from the roof at Notre-Dame Cathedral April 15, 2019 in Paris, France. (Photo by Pierre Suu/Getty Images)

People look a fire at the landmark Notre-Dame Cathedral in central Paris from the banks of the Seine river on April 15, 2019. (Photo by Thomas SAMSON / AFP)

Smoke and flames rise during a fire at the landmark Notre-Dame Cathedral in central Paris on April 15, 2019, potentially involving renovation works being carried out at the site, the fire service said. (Photo by FRANCOIS GUILLOT / AFP)

Firefighters tackle the blaze as flames and smoke rise from Notre Dame cathedral as it burns in Paris, Monday, April 15, 2019. (AP Photo/Michel Euler)

Smoke and flames rise during a fire at the landmark Notre-Dame Cathedral in central Paris on April 15, 2019, potentially involving renovation works being carried out at the site, the fire service said. (Photo by Hubert Hitier / AFP)

A woman reacts as she watches flames engulf the roof of the Notre-Dame de Paris Cathedral in the French capital Paris on April 15, 2019.(Photo by GEOFFROY VAN DER HASSELT / AFP)

Notre Dame cathedral is burning in Paris, Monday, April 15, 2019. Massive plumes of yellow brown smoke is filling the air above Notre Dame Cathedral and ash is falling on tourists and others around the island that marks the center of Paris. (AP Photo/Lori Hinant)

Flames and smoke billow from the roof at Notre-Dame Cathedral in Paris on April 15, 2019. (Photo by Thomas SAMSON / AFP)

Flames rise from Notre Dame cathedral as it burns in Paris, Monday, April 15, 2019. (AP Photo/Thibault Camus)

Firefighters are seen inside famed Notre-Dame Cathedral assessing the damage caused by fire on April 15, 2019 in Paris, France. Photo by Omar Havana / Getty Images

Fire rages through the iconic Notre-Dame Cathedral on April 15, 2019 in Paris, France. (Photo by Philippe Wang/Getty Images)

Flames and smoke are seen billowing from the roof at Notre-Dame Cathedral in Paris on April 15, 2019. (Photo by Fouad Maghrane / AFP)

Firefighters douse flames rising from the roof at Notre-Dame Cathedral in Paris on April 15, 2019. (Photo by LUDOVIC MARIN / AFP)

Firefighters douse flames rising from the roof at Notre-Dame Cathedral in Paris on April 15, 2019. (Photo by Bertrand GUAY / AFP)

Smoke and flames rise from Notre-Dame Cathedral on April 15, 2019 in Paris, France. (Photo by Veronique de Viguerie/Getty Images)

Flames and smoke are seen billowing from the roof at Notre-Dame Cathedral on April 15, 2019 in Paris, France. (Photo by Chesnot/Getty Images)

People stand on a bridge looking at smoke and flames rising during a fire at the landmark Notre-Dame Cathedral in central Paris on April 15, 2019. (Photo by Thomas SAMSON / AFP)

A firefighter uses a hose to douse flames and smoke billowing from the roof at Notre-Dame Cathedral in Paris on April 15, 2019.(Photo by GEOFFROY VAN DER HASSELT / AFP)

Firefighters assemble their hoses as they gather at the River Seine near Notre-Dame de Paris Cathedral as flames engulf the roof of the cathedral on April 15, 2019, in the French capital Paris. (Photo by STEPHANE DE SAKUTIN / AFP)

Smoke and flames are seen in the interior of Notre Dame cathedral in Paris, Monday, April 15, 2019. (Philippe Wojazer/Pool via AP)

People react as they watch flames engulf the roof of the Notre-Dame de Paris Cathedral in the French capital Paris on April 15, 2019. (Photo by GEOFFROY VAN DER HASSELT / AFP)

A firefighter is seen fighting the flames at Notre-Dame Cathedral April 15, 2019 in Paris, France. (Photo by Pierre Suu/Getty Images)

A firefighter tackles the blaze as flames and smoke rise from Notre Dame cathedral as it burns in Paris, Monday, April 15, 2019. (AP Photo/Michel Euler)

Smoke and flames rise during a fire at the landmark Notre-Dame Cathedral in central Paris on April 15, 2019, potentially involving renovation works being carried out at the site, the fire service said. (Photo by FRANCOIS GUILLOT / AFP)

A huge destructive fire engulfs the famous Notre Dame cathedral in Paris, France. Picture by: AbacaPress / SplashNews.com

A huge destructive fire engulfs the famous Notre Dame cathedral in Paris, France. Picture by: AbacaPress / SplashNews.com

General view from the entrance of Notre Dame cathedral in Paris, Monday, April 15, 2019. (Philippe Wojazer/Pool via AP)

Notre Dame cathedral is burning in Paris, Monday, April 15, 2019. (AP Photo/Rafael Yaghobzadeh)

Smoke and flames rise during a fire at the landmark Notre-Dame Cathedral in central Paris on April 15, 2019, potentially involving renovation works being carried out at the site, the fire service said. (Photo by Hubert Hitier / AFP)

Flames and smoke are seen billowing from the roof at Notre-Dame Cathedral in Paris on April 15, 2019. (Photo by STRINGER / AFP)

Flames and smoke are seen billowing from the roof at Notre-Dame Cathedral in Paris on April 15, 2019. (Photo by Fouad Maghrane / AFP)

Flames and smoke are seen billowing from the roof at Notre-Dame Cathedral in Paris on April 15, 2019. (Photo by Fouad Maghrane / AFP)

Flames and smoke are seen billowing from the roof at Notre-Dame Cathedral in Paris on April 15, 2019. (Photo by Patrick ANIDJAR / AFP)

Flames and smoke are seen billowing from the roof at Notre-Dame Cathedral in Paris on April 15, 2019. (Photo by Patrick ANIDJAR / AFP)

A fire fighter is seen dousing the facade of the Notre-Dame de Paris Cathedral as flames engulf the roof of the cathedral on April 15, 2019, in the French capital Paris. (Photo by STEPHANE DE SAKUTIN / AFP)

Firefighters douse flames rising from the roof at Notre-Dame Cathedral in Paris on April 15, 2019. (Photo by Bertrand GUAY / AFP)

Smoke and flames rise during a fire at the landmark Notre-Dame Cathedral in central Paris on April 15, 2019. (Photo by FRANCOIS GUILLOT / AFP)

Flames and smoke rise as the spire on Notre Dame cathedral collapses in Paris, Monday, April 15, 2019. (AP Photo/Diana Ayanna)

Flames and smoke rise as the spire on Notre Dame cathedral collapses in Paris, Monday, April 15, 2019. (AP Photo/Diana Ayanna)

Flames and smoke rise as the spire on Notre Dame cathedral collapses in Paris, Monday, April 15, 2019. (AP Photo/Diana Ayanna)

The steeple collapses as smoke and flames engulf the Notre-Dame Cathedral in Paris on April 15, 2019. (Photo by Geoffroy VAN DER HASSELT / AFP)

A woman reacts as she watches the flames engulf the roof of the Notre-Dame Cathedral in Paris on April 15, 2019. (Photo by Geoffroy VAN DER HASSELT / AFP)

People watch as flames and smoke rise from Notre Dame cathedral as it burns in Paris, Monday, April 15, 2019.(AP Photo/Thibault Camus)

Flames and smoke are seen billowing from the roof at Notre-Dame Cathedral on April 15, 2019 in Paris, France. (Photo by Veronique de Viguerie/Getty Images)

Flames and smoke are seen billowing from the roof at Notre-Dame Cathedral on April 15, 2019 in Paris, France. (Photo by Veronique de Viguerie/Getty Images)

This general view from the entrance shows smoke rising in front of the altar cross at Notre-Dame Cathedral in Paris on April 15, 2019, after a fire engulfed the building. (Photo by PHILIPPE WOJAZER / POOL / AFP)

A firefighter is seen fighting the flames at Notre-Dame Cathedral April 15, 2019 in Paris, France.(Photo by Pierre Suu/Getty Images)

Firefighters continue to work at the site for inspection after the fire at the Notre Dame cathedral in Paris, France on April 15, 2019. (Photo by Mustafa Yalcin/Anadolu Agency/Getty Images)

Firefighters tackle the blaze as flames and smoke rise from Notre Dame cathedral as it burns in Paris, Monday, April 15, 2019. (AP Photo/Thibault Camus)

Notre Dame cathedral is burning in Paris, Monday, April 15, 2019. A catastrophic fire engulfed the upper reaches of Paris' soaring Notre Dame Cathedral as it was undergoing renovations Monday, threatening one of the greatest architectural treasures of the Western world as tourists and Parisians looked on aghast from the streets below. (AP Photo/Francois Mori)

Smoke and flames rise during a fire at the landmark Notre-Dame Cathedral in central Paris on April 15, 2019. Picture: Eliot Blondet /ABACAPRESS.COM/AAP

French firemen enter the Notre-Dame Cathedral as flames are burning the roof cathedral in Paris, France, 15 April 2019. EPA/YOAN VALAT

Smoke and flames rise during a fire at the landmark Notre-Dame Cathedral in central Paris, France on April 15, 2019. Photo by Aurore Marechal/ABACAPRESS.COMA/AAP

Smoke and flames rise during a fire at the landmark Notre-Dame Cathedral in central Paris on April 15, 2019, potentially involving renovation works being carried out at the site, the fire service said. Photo by Eliot Blondet /ABACAPRESS.COM/AAP

French fire fighters open water supply points as others douse a fire that engulfed the roof of the Notre-Dame de Paris Cathedral on April 15, 2019 in Paris. Picture: GEOFFROY VAN DER HASSELT / AFP

Flames illuminate the night sky as Notre Dame cathedral burns in Paris, Monday, April 15, 2019. (AP Photo/Thibault Camus)

A speedboat travels down the river Seine as flames and smoke rise from Notre Dame cathedral as it burns in Paris, Monday, April 15, 2019. (AP Photo/Thibault Camus)

Flames and smoke rise from Notre Dame cathedral as it burns in Paris, Monday, April 15, 2019. (AP Photo/Thibault Camus)