"He ordered me to put in [the report] the specific positions of the national police which I had not seen on the screen," she was quoted as saying.

A senior policewoman claimed on Sunday that France’s Interior Minister pressured her to alter a report into security at the Nice fireworks display where 84 were killed when a man rammed a lorry into the crowd.

But the Minister, Bernard Cazeneuve —— whose account of police deployments on the night of July 14 has already faced questions —— hit back at the “grave accusations” and said he would sue for defamation.

Sandra Bertin, who is in charge of Nice’s system of security cameras, told the Journal du Dimanche newspaper she had been “harassed for an hour” by Mr. Cazeneuve on the phone after he sent a commissioner to see her.

She said she had been told to detail the presence of the local police at the Bastille Day fireworks event and also to report “that the national police had also been deployed at two points”.

“The national police were perhaps there, but I couldn’t see them on the video,” Ms. Bertin told the newspaper.

“He ordered me to put in [the report] the specific positions of the national police which I had not seen on the screen,” she was quoted as saying.

On Thursday, the left-leaning Liberation daily reported that only one local police car was barring the entry to the seafront pedestrian zone when Mohamed Lahouaiej Bouhlel forced his lorry onto the Promenade des Anglais, mowing down families.

Since the carnage 10 days ago —— the third major attack in France in 18 months —— Mr. Cazeneuve has also been locked in an escalating row with the right-wing leaders of the Riviera city over claims of slack security.

President Francois Hollande was forced on Friday to say that he still had “full confidence” in his key minister, promising “truth and transparency” on the security measures that were in place.