A major fire has caused extensive damage to Notre-Dame cathedral in Paris, one of the city's best known landmarks.

Flames that began in the early evening burst rapidly through the roof of the centuries-old cathedral and engulfed the spire, which collapsed, quickly followed by the entire roof.

A huge plume of smoke wafted across the city and ash fell over a large area. Parisians watched on, many of them lost for words.

Paris police said tonight that the structure of the cathedral had been saved, and the fire has been stopped from spreading to the northern belfry. 

Prosecutors believe the fire started accidentally, based on their preliminary investigation.

Paris fire commander Jean-Claude Gallet said a major accomplishment of hundreds of fire fighters was stopping the flames from spreading to the north tower belfry.

He said two-thirds of Notre Dame's roofing "has been ravaged" and one fire fighter was injured.

Fire crews will keep working overnight to cool down the structure, Mr Gallet said. 

Fire crews inside Notre-Dame cathedral tonight

French President Emmanuel Macron said tonight that the cathedral will be rebuilt.

Speaking at the scene of the blaze he said: "We will rebuild Notre-Dame."

He said "the worst has been avoided" thanks to the work of the fire crews and he vowed to draw on the "best talent" to complete the reconstruction works.

Speaking at the scene, President Macron said Notre-Dame would be rebuilt

President Macron said that "starting tomorrow" he would launch an international appeal for the restoration of the beloved church.

"And we will rebuild Notre-Dame because it is what the French expect," he said.

He also expressed his sympathy with Catholics around the world on what had been a "terrible tragedy".

Firefighters tried to contain the blaze with water hoses and cleared the area around Notre-Dame, which sits on an island in the River Seine and marks the very centre of Paris.

World leaders have been expressing their sadness about the destruction caused by the blaze.

Here, President Michael D Higgins said Notre-Dame cathedral was a building which the people of Paris have shared with millions from all over the world, as part of a shared global cultural heritage.

He said, "As President of Ireland I would like to express the feelings of solidarity of the Irish people with the people of France at the catastrophic damage to one of the most iconic buildings in Europe."

President Higgins added: "The Notre-Dame Cathedral has suffered many instances of catastrophic damage over the centuries, and it is my hope that it will survive this latest terrible catastrophe."

The Vatican issued a statement that said: "The Holy See has seen with shock and sadness the news of the terrible fire that has devastated the Cathedral of Notre-Dame, symbol of Christianity in France and in the world."

The statement said the Vatican is praying for firefighters "and those who are doing everything possible to confront this dramatic situation".

Meanwhile, the Archbishop of Armagh and Catholic Primate of All Ireland, Eamon Martin has tweeted that it is heartbreaking to see the sacred and historic Notre Dame cathedral engulfed in flames. He said he was sending prayers from Ireland to Archbishop Michel Aupetit and the people of Paris.

The Louvre Museum has described the blaze as "a tragedy for World Heritage".

A comment on the art museum's official Twitter account said: "The fire which has struck Notre Dame Cathedral in Paris is a tragedy for World Heritage.

"The Louvre expresses its deepest admiration and solidarity with those who are currently battling the flames." 

A UNESCO World Heritage site

The cathedral, which dates back to the 12th century, features in Victor Hugo's classic novel "The Hunchback of Notre-Dame". It is a UNESCO World Heritage site that attracts millions of tourists every year.

The cathedral was in the midst of renovations, with some sections under scaffolding, and bronze statues were removed last week for works.

Built over a century starting in 1163, Notre-Dame is considered to be among the finest examples of French Gothic cathedral architecture.

Its 100-metre-long (330-foot) roof, of which a large section was consumed in the first hour of the blaze, was one of the oldest such structures in Paris, according to the cathedral’s website.

A centre of Roman Catholic faith, over the centuries Notre-Dame has also been a target of political upheaval.

It was ransacked by rioting Protestant Huguenots in the 16th century, pillaged again during the French Revolution of the 1790s and left in a state of semi-neglect. Hugo’s 1831 work led to revived interest in the cathedral and a major – partly botched - restoration that began in 1844.

The wood-and-lead spire was built during that restoration, according to the cathedral's website.

UNESCO said in a tweet it was "closely monitoring the situation and is standing by France's side to safeguard and restore this invaluable heritage".