BERLIN (AFP) - A leader of Germany's far-right AfD party on Tuesday (April 16) tried to link the devastating fire at Paris's Notre Dame cathedral to rising "intolerance" against Christians in Europe, although French investigators believe the inferno was an accident.

In a tweet, Ms Alice Weidel, the parliamentary group leader of the Alternative for Germany (AfD), the country's largest opposition party, implied a connection between the blaze which broke out on Monday (April 15) evening and previous anti-Christian "attacks" in France.

"During Holy Week #NotreDame burns. March: second largest church Saint-Sulpice burns. February: 47 attacks in France," Ms Weidel wrote.

"The Observatory on Intolerance and Discrimination Against Christians in Europe speaks of a significant increase," she added, including a link to a March article in a German Catholic magazine headlined "Catholic churches desecrated across France".

The Notre Dame blaze, which brought the iconic building's towering spire and roof crashing down, is being treated by French investigators as an "involuntary fire" and they have advanced no other theory.

The cathedral had been undergoing intensive restoration work which firefighters said could be linked to the inferno.

The brief fire on March 17 at Saint-Sulpice, a Roman Catholic church in Paris, left no one hurt and little damage. Investigators have opened an inquiry into the blaze.

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The Observatory on Intolerance and Discrimination Against Christians in Europe cited by Ms Weidel is a non-governmental organisation based in Austria.

It could not immediately be reached by AFP but did not raise any suspicion of an anti-Christian act behind the Notre-Dame blaze on any of its online platforms.

The AfD, which holds more than 90 seats in the Bundestag lower house of parliament, rails against Islam and Muslim immigrants as a threat to Christian culture in Germany and Europe.