French prosecutors say there is raft of evidence suggesting that the man arrested for last week’s train attack carefully prepared a jihadist assault that would have ended in carnage had passengers not intervened.

Ayoub El-Khazzani, a Moroccan national, boarded a high-speed train in Brussels on Friday armed with a Kalashnikov assault rifle, 270 rounds of ammunition, a Luger pistol, a bottle of petrol and a box-cutter, according to Paris prosecutor Francois Molins.

A Franco-American man was shot and injured in the attack, which Mr Molins described as “targeted and premeditated”.

• Frances bestows top honour on train heroes
• As train crew flee, American tourists become heroes
• President Obama thanks train heroes

Mr Khazzani’s claims to investigators that he was only planning to rob passengers were “barely credible”, said Mr Molins, adding that he had grown increasingly evasive in his responses to police and stopped responding entirely on Monday.

Mr Molins outlined a raft of evidence indicating why Mr Khazzani was being probed for “attempted murder” as part of a terrorist plot.

This included the fact that Mr Khazzani flew back in June from a town in southern Turkey — “a possible passageway into Syria” — and that he watched a video “calling for violent acts in the name of radical Islam” on his phone prior to launching the attack.

Mr Molins also raised suspicions about how Mr Khazzani was able to afford a 149 euro ($240) first class train ticket, given his claims to be sleeping rough in Brussels.

Ticket sellers at the station have told investigators that Mr Khazzani paid in cash and turned down an earlier journey where seats were available, which Mr Molins said was an indication the target had been carefully chosen in advance.

He also dismissed as “absurd” claims by the suspect that he found the stash of weapons and mobile phone in a park where he was sleeping rough the night before.

And he said that Mr Khazzani’s Facebook page had mysteriously been disabled on Saturday — the day after the foiled attack.

In footage caught by the iTele network, Mr Khazzani was seen arriving at the Paris courthouse on Tuesday — where a magistrate was due to decide whether or not to charge him — flanked by policemen, barefoot, handcuffed and with a mask over his eyes.

French authorities have until Tuesday evening to charge or release Mr Khazzani, who has reportedly also been on the radar of several European intelligence agencies.