France's interior minister rejected on Sunday an assertion by a senior Nice security official that his staff tried to change a report into policing on the night of the Bastille Day attack that claimed 84 lives.
France's Socialist government has come under fire for not doing enough to prevent a delivery man from ploughing a refrigerator truck into a crowd of revellers leaving a July 14 fireworks display on the Riviera city's beachfront promenade.
Interior Minister Bernard Cazeneuve said he would file a defamation lawsuit after the head of Nice's extensive video surveillance network said in a newspaper interview that someone from his staff had sought changes to her report.
Led by regional government president Christian Estrosi, conservative politicians from Nice have aggressively questioned whether officers from the national police were present in sufficient numbers on the night of the attack.
The government has repeatedly rejected this accusation.
"For ten days now, we have nearly every day faced attacks, insinuations and lies from some of those bearing political responsibility in Nice," the normally unflappable Cazeneuve said with visible agitation on France 2 television.
Nice, a city of nearly 350,000 people, is France's most heavily policed city with nearly 600 officers municipal police officers and other security agents - more than much larger cities - and an extensive network of surveillance cameras.
Sandra Bertin, head of Nice's video surveillance network, told the Journal du Dimanche newspaper that someone from Cazeneuve's staff had ordered her the day after the attack to say that officers from national police force were present at certain places where the attack had occurred.
"I dealt with someone who wanted a report indicating where there were municipal police, road barriers and also clearly stating that national police could be seen at two points," she said.
"Maybe national police officers were there, but they could not be seen in the videos," she said, adding that the ministry official harassed her for an hour on the subject.