Links between Mohamed Lahouaiej Bouhlel, the driver of a truck who killed at least 84 people by using a lorry to mow down civilians on a busy Nice street during Bastille Day celebrations, and the Islamic State (Isis), which claimed the attack, "are not established," France's Interior Ministry has claimed.

The terror group made the claim through its propaganda arm, the Amaq News Agency. Citing a "security source" the terrorist organisation said Lahouaiej-Bouhlel "carried out the operation in response to calls to target the citizens of coalition countries fighting the Islamic State".

There is a debate in France around whether Lahouaiej-Bouhlel's attack was motivated by Islamist beliefs or mental illness. While it emerged "loner" Lahouaiej-Bouhlel consumed alcohol and pork in defiance of Islamic beliefs, he also allegedly visited Islamist terror websites in recent months and is heard on film footage screaming "Allahu Akbar".

'Links between attacker and ISIS' not established

Four days after the attack, however, the interior minister, Bernard Cazeneuve said: "We need to know now what the links are between the person who committed this despicable attack and terrorist networks. For now, these links have not been established by the investigation."

Speaking on RTL radio, Cazeneuve said that the attack bore "completely the message of Daech [Arabic acronym of the Islamic state]."

While the attack was reportedly premeditated, French investigators are yet to find whether or how Lahouaiej-Bouhlel may have been radicalised by the Islamist militancy.

"We cannot exclude that an unbalanced and very violent individual, and it seems that his psychology demonstrates these traits, was at one time, in a rapid radicalisation, (was) committed to this absolutely appalling crime," Cazeneuve said on Monday (18 July).

The interior minister had previously said that the truck driver "appear(ed) to have radicalised very quickly".

Mohamed Lahouaiej-Bouhlel
ID for Mohamed Lahouaiej-Bouhlel Broadcast outlets

Cazeneuve: Government did do enough to fight terrorism

Former French president Nicolas Sarkozy, meanwhile, has accused his successor Francois Hollande "of not doing enough" in the fight against terrorism in the prior 18 months before the attack.

The leader of the Republicans party said Hollande had confronted the jihadist threat with "trembling hands" after the third major Islamist attack in the country in 18 months.

Responding to Sarkozy, Cazeneuve claimed that, on the contrary, "many things [had] changed." The minister of the interior listed the "many steps" the government had taken, such as a rise in security and intelligence services staff with the creation of 9,000 jobs and the adoption of three anti-terrorism laws.

Three people were arrested on Sunday (17 July), bringing to seven the number of people held in custody in connection with the attack. Among them, a couple of Albanians of which a man is suspected of having provided the 7.65 gun used by the attacker. Four other people − relatives − were arrested and remained in custody on Sunday. Investigators are also looking to interpret the meaning of several confused text messages sent by Lahouaiej Bouhlel on the day of the attack.

According to the latest reports, the attack on Nice left 84 dead and 308 wounded − with 58 people still hospitalised, including 29 in intensive care.