“Everything would have collapsed,” said Lieutenant-Colonel Michael Bernier, a fire chief who speaks for the national civil defence organisation and who described the suggestion as “risible”.

Releasing even one load from a Canadair water bomber used to fight forest fires on Notre-Dame would be “the equivalent of dropping three tonnes of concrete at 250 kilometres per hour (155mph)” on the ancient monument.

“It would have been like bowling with the cathedral… the two towers might have fallen.

“It was technically impossible, undoable and most of all would have been utterly useless” to douse the flames from the air, Bernier added.