France probes security failings

French President Francois Hollande on Thursday promised "truth and transparency" from an inquiry into allegations of lax security the night of the Bastille Day attack in Nice that killed 84 people.

"When there is a tragedy, or in this case an attack with many dead... there will naturally be questions," Hollande said during a visit to Dublin, adding that the conclusions of the police probe would be announced next week.

The third major attack in France in 18 months has left France’s Socialist government fending off accusations of failing to protect the nation.

Liberation daily reported on Thursday that only one municipal police car was guarding the spot where Mohamed Lahouaiej Bouhlel crashed a 19-tonne truck through barriers and into crowds on the promenade.

A week after the rampage, five suspects arrested over links to the Tunisian attacker are to appear before anti-terrorism judges who will decide whether to charge them.

The attack came just as France was preparing to lift the state of emergency in place since the November attacks in Paris, prompting an immediate reversal of course.

On Thursday, parliament finalised adoption of a bill extending the emergency laws for a fourth time, after it was toughened up by the right-dominated Senate.

The final version bans gatherings where sufficient security cannot be provided and makes it easier to shut places of worship where preachers incite hate or violence.

Since November the authorities have had emergency powers to carry out searches by day or night and place people under house arrest.

While France continues to mourn the victims of the assault that took terror to the shores of the Riviera, the government continues to be plagued by questions over possible security failings.

Prime Minister Manuel Valls has accused members of the centre-right Republicans party of "lying to the French" after some suggested the attack could have been thwarted.

Just hours after he warned the French had to learn to live with terror, the Islamic State (IS) group -- which claimed the Nice attack -- posted a video showing two French-speaking jihadists threatening more attacks against the country. The video appeared to have been shot in Iraq. IS last week claimed Bouhlel as one of its "soldiers".

Investigators have said they have no proof yet that the driver, who was shot dead by police, had pledged allegiance to the group.

In Nice, investigators found a Kalashnikov rifle and a bag of ammunition in the basement of a 22-year-old man who is among five being held over links to Bouhlel.

The suspect received text messages from Bouhlel on the night of the attack, in which Bouhlel praised him for providing the pistol he used during a shootout with police.

All five suspects are to appear before a judge Thursday to face possible charges. About 100 investigators are poring over masses of data linked to the probe.

Pictures found on Bouhlel’s mobile phone indicate he was studying several locations where crowds gathered as possible targets.