Nice attack: French interior minister backtracks on claims heavily-armed police were present during massacre

French newspaper Liberation claims Mr Cazeneuve lied about the whereabouts of national police officers and cars – something he and other ministers emphatically deny

French Interior minister Bernard Cazeneuve at the National Assembly in Paris yesterday (AFP/Getty)

France's interior minister has backtracked on his claim national police were stationed at the entrance to the promenade in Nice where the Bastille Day truck attack took place.

In a speech two days after the attack, Bernard Cazeneuve said "national police were present and very present on the Promenade des Anglais". He also suggested their cars were blocking the walkway entrance when Mohamed Lahouaiej Bouhlel drove a 19-metric ton (20-ton) truck onto the promenade killing 84 people before police shot him dead.

However, Mr Cazeneuve has now said local police, who are more lightly armed than national police, were guarding the entrance to the area.

He has also launched an internal police investigation into the handling of the attack, to be published next week.

French newspaper Liberation has claimed Mr Cazeneuve lied about the whereabouts of the national police officers and cars, and accused French authorities of lacking transparency.

Using witness statements and photos in its Thursday edition, Liberation claimed that only one local police car was stationed at the entrance to the walkway.

The paper quotes local police officer Yves Bergerat, who said the guns and bullets of the local force are not even equipped "to puncture the tires".

Mr Cazeneuve accused the paper of conspiracy theories and maintained that several "heroic" national police – who killed the attacker after an exchange of fire – were stationed further down the promenade.

French Prime Minister Manuel Valls joined a chorus of officials defending themselves against the charges, and made a public show of support for Mr Cazeneuve in whom, he said, he had full trust.

“Lies debase public debate ... the government has nothing to hide,” Mr Valls said.

"There's no room for polemics, there's only room for transparency," French President Francois Hollande said. "The necessary, serious preparations had been made for the July 14 festivities."

He added: “If there were any shortcomings they will come to light.”

Much of the criticism, beyond the system of road blocks easily breached by the truck, centres a complex command structure where some units of police answer to local government and others to central government.

The inquiry will look into the details of how the area was cordoned off for the traditional Bastille Day festivities and how the area was patrolled.

“I welcome the interior minister's decision to order an inquiry of the Nice attack by the police of police,” tweeted Christian Estrosi, the head of the regional government in the southeast Riviera coast area who has led the criticism.

The right-wing politician has accused the Socialist administration of not doing enough to protect the public.

Nice police department chief Adolphe Colrat, who answers to central government rather than the regional politicians who are leading the criticism, said the authorities had “at no time” lied or misled people on policing arrangements.

Elsewhere, the Paris prosecutor has said the attacker, Mohamed Lahouaiej Bouhlel, had been plotting his attack for months. .

Prosecutor Francois Molins said his office, which oversees terrorism investigations, said five suspects currently in custody are facing preliminary terrorism charges for their alleged roles in helping driver in a judicial inquiry opened on Thursday.

Mr Molins said information from Bouhlel's phone showed searches and photos that indicated he had potentially been planning an attack since 2015.

Additional reporting by agencies