PARIS (AFP) - They were celebrated as heroes when they pummelled a heavily-armed jihadist with their bare hands to foil a train terror attack in France in 2015.

But the three childhood friends who play themselves in Clint Eastwood's Hollywood reconstruction of the drama took a battering from critics when the film opened in France on Wednesday (Feb 7).

Only in the final "incredible, hyper-tense 10 minutes" does The 15:17 To Paris take off, said the Parisien newspaper.

Another critic lamented that "the movie gets stuck in the station".

The film has also upset the Moroccan's lawyers, with judges yet to deliver their verdict.

"That Hollywood has delivered its 'truth' before the judges is at the very least worrying," Ms Sarah Mauger-Poliak told French radio.

The Moroccan was armed with an AK-47 on the Paris-bound train from Amsterdam that was carrying more than 500 passengers.

Eastwood's last two films - Sully and American Sniper - were also about real-life heroes, but this is the first time he has used the real protagonists to play themselves.

He said he wanted to "make people aware that they have the strength to do (extraordinary) things themselves".

"There could have been a lot of people killed, (the attacker) had a lot of ammunition, he had a very reliable gun," Eastwood added.