Investigators believe an 'electrical short circuit' was responsible for starting the blaze which devastated Notre Dame cathedral this week.

A French judicial police official said investigators brought in to work out the cause of the inferno made the claims - despite them not having been given access to the church yet for safety reasons.

The official, who spoke anonymously about the ongoing investigation, said the monument is still being consolidated with wooden planks to support some fragile parts of the walls.

Only after it is fully made safe will investigators will be allowed a closer look in order to accurately determine the cause of the fire.

A French scaffolding company working on Notre Dame's roof revealed it installed a timelapse camera at 2pm the day of the fire, and say it may contain clues about how the blaze started

Meanwhile firefighters who helped save the cathedral arrived at the Elysee Palace in Paris to meet with President Macron

Mr Macron was due to praise the fire crews for their efforts in tackling the blaze, which saved the structure of the building along with its rose windows and organ

Scaffolding was hoisted into place at Notre Dame cathedral on Thursday as $1billion restoration work got underway

Earlier on Thursday, police released time lapse footage from a camera installed just hours before Monday's devastating blaze which was believed to contain vital clues as to what caused the inferno.

The camera was installed around 2pm by French scaffolding company Europe Echafaudage and was set to take photographs every 10 minutes. The fire broke out around 6.40pm.

Marc Eskenazi, a representative for Echafaudage, confirmed that smoke can be seen on some of the images and appears to start on the south side of the building.

The camera will not reveal the exact cause of the fire and where it started, Eskenazi said, but will point investigators in the direction of vital clues.

The camera is now in the hands of investigators.

Europe Echafaudage was one of five companies contracted to restore the cathedral's landmark spire, which was timber-framed and towered 295 feet (90 metres), shaping the skyline along the Seine river.

French President Emmanuel Macron (left) speaks with Notre Dame's rector Patrick Chauvet on Wednesday after meetings on the reconstruction at the Elysee Palace

French Interior Minister Christophe Castaner (left), First Lady Brigitte Macron and Chauvet arrive to attend a mass, as part of the Holy Week, at the Saint Sulpice Church in Paris on Wednesday

The fire consumed Notre-Dame's roof, whose oak beams dated back to the thirteenth century, and sent its spire crashing through the cathedral's vaulted ceiling.

The damage to one of France's best loved monuments prompted an outpouring of national sorrow and a public desire for quick answers over where and how the blaze started.

Paris public prosecutor Remy Heitz has said the fire appeared accidental. His office did not respond to a request for comment on the time-lapse images photographs.

The news emerged as Paris firefighters began arriving at the Elysee Palace for a meeting with Emmanuel Macron.

The French President was due to praise them for their efforts in tackling the blaze, which saw the three rose windows and pipe organ saved from the flames.

Meanwhile Bishop Patrick Chauvet, the rector of Notre Dame called for a temporary cathedral to be built for Catholics outside the ruined building while restoration work takes place.

Mr Chauvet spoke of an 'ephemeral cathedral' to stand outside the holy site after Macron said Notre Dame's rebuilding would take five years.

Speaking to CNews Chauvet said: 'We mustn't say "the cathedral is closed for five years and that's it,"' suggesting, 'Can I not build an ephemeral cathedral on the esplanade (in front of Notre-Dame)?'

French firefighters pull supplies and hoses from their trucks outside Notre Dame on Monday night

Chauvet said the wooden church would host priests who could address some of the millions of tourists who throng the original 850-year-old Gothic cathedral each year.

The Bishop said the surrogate 'cathedral' would be erected quickly, as soon as the esplanade reopens after work to secure the cathedral is completed.

Donations rising to a billion euros have been added to the rebuilding project, including free flights from France-KLM to those participating in the project.

In a statement the airline said: 'Air France will provide free transport for all official partners involved in the reconstruction of Notre-Dame cathedral in Paris.'

The blaze which tore down the cathedral's steeple and much of its roof, would have been far worse if not for Paris' brave firefighters who Macron will meet on Thursday.

The president is to host them for a special gathering to share 'words of thanks', according to his office.

French firefighters at the scene of Monday's fire at Notre Dame cathedral

Senior government ministers will also take part in the event at the presidential palace in Paris.

Later, Paris City Hall will hold a ceremony in the firefighters' honour, with a Bach violin concert, two giant banners strung from the monumental city headquarters and readings from Victor Hugo's The Hunchback Of Notre Dame.

More than 400 firefighters took part in the nine-hour battle to save the 12th-century cathedral on Monday evening.

They were able to save the iconic belfries, rose windows, organ and precious artworks.

No one was killed in the fire, which occurred during a mass, after firefighters and church officials speedily evacuated the building.

Among those to be honoured is Paris fire brigade chaplain Jean-Marc Fournier, who helped salvage the crown of thorns believed to have been worn by Jesus at his crucifixion.

Another is Myriam Chudzinski, among the first firefighters to reach the roof as the blaze raged.

Loaded with gear, they climbed hundreds of steps up a narrow spiral staircase to the top of one of the two towers. She had trained at the cathedral for just this moment.

Firefighters stand in tall crane as they tackled the ferocious inferno on Monday evening

'We knew that the roof was burning, but we didn't really know the intensity,' she told reporters.

'It was from upstairs that you understood that it was really dramatic. It was very hot and we had to retreat, retreat. It was spreading quickly.'

She heard a roar, but her focus was on saving the tower. She learned later that it was the sound of the spire collapsing.

Investigators believe the fire was accidental and are questioning cathedral staff and workers who were carrying out renovations to the building before the fire broke out.

Some 40 people have been questioned and some are being quizzed again on Thursday, according the Paris prosecutor's office.

Fire officials warn that the massive cathedral remains fragile, and are removing statues above the rose windows to keep them from falling.

Fire fighters line up as they wait for French Interior Minister Christophe Castaner outside Notre on Tuesday

French Interior Minister Christophe Castaner, right, greets firefighters outside Notre cathedral in Paris on Tuesday

The building would have burned to the ground in a 'chain-reaction collapse' had firefighters not moved as rapidly as they did to battle the blaze, said Jose Vaz de Matos, a fire expert with the Culture Ministry.

An initial fire alert was sounded at 6.20pm as a mass was under way in the cathedral, but no fire was found. A second alarm went off at 6.43pm and the blaze was discovered on the roof.

Mr Macron wants to rebuild the cathedral within five years - in time for the 2024 Summer Olympics that Paris is hosting - but experts have questioned whether that is realistic, given the vast scale of the work.

One said the rebuilding project would easily take 15 years. More than £750 million has been pledged for the restoration.