A hero motorcyclist has told of his frantic bid to stop ISIS truck terrorist Mohamed Bouhlel by trying to jump from his bike and onto the lorry as it ploughed at high speed into crowds in Nice.

In an act of astonishing bravery, Alexander Migues sped his bike alongside the 19-tonne truck as Bouhlel ran over 84 people watching fireworks on Bastille Day.

Speaking for the time, he revealed how he leapt onto the moving death machine and clung on as he tried to wrestle the driver's-side door open several times as the truck sped along the promenade.

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Alexander Migues has spoken for the first time about the events which led up to the horrific massacre in Nice

Alexander Migues sped his bike (circled) alongside the 19-tonne truck as Bouhlel ran over 84 people watching fireworks on Bastille Day

'I saw the truck rise (over the median strip) and run over a lady, he told Nice Martin.

'He was on the sidewalk and then he returned to the road and he tried to run me over too,' he said.

'It was instinctive, I cannot even explain how I managed to go chasing a truck. When I saw that he was really determined, I tried something,' Migues said

Despite his bravery, Migues was forced to abandon his attempt when the terrorist pulled a gun on him.

The Frenchman has been credited with saving lives by slowing the truck enough to give another motorcyclist time to throw his scooter under the wheels of the lorry.

The dramatic attempt to stop Bouhlel made headlines around the world after the life-and-death struggle was captured on video.

'He arrived in a scooter and threw it under the wheels of the truck to stop. I let go of the door and when the scooter tapped the truck I heard the noise of bullets,' Migues said.

Migues desperately tried to stop Mohamed Bouhlel by trying to jump from his bike and onto the lorry as it ploughed along the road at high speed

Migues remains traumatised by the experience and says he didn't sleep for the first 36 hours after the attack and now has nightmares.

He said he wished he could have hung onto the truck longer and slowed it more so that victims would have had more time to flee its deadly path.

But he can take comfort that the time when the scooter went under the truck to when the police engaged in a firefight there were no more killed.

'For 36 hours I did not sleep, then it gets a bit better. But when I wake up I take my bike or I do drive roundtrips to clear my mind,' he said.

Teddy bears, toy elephants, plush rabbits and heartbreakingly a child's drawing of young children with angel wings have dominated the myriad candlelit memorials that have sprung up the length of the Promenade.