PARIS — The Islamist gunman who killed four people in southern France last week had been summoned by anti-terror police for questioning shortly before his shooting rampage, a police source told AFP on Tuesday.

Radouane Lakdim, a 25-year-old Moroccan-born French national, had been on a list of suspected extremists since 2014 and was being monitored, leading to criticism of the security services from some politicians over their failure to prevent the attack.

Lakdim killed four people and injured four others on Friday in three separate shootings in the towns of Carcassonne and nearby Trebes, where he took hostages at a supermarket before being shot by anti-terror police.

The police source, who spoke on condition of anonymity, said that Lakdim had been sent a letter in March asking him to arrange a face-to-face meeting with agents from France’s domestic intelligence agency DGSI.

Lakdim’s 18-year-old girlfriend, a radicalised Muslim convert who was detained after the attack, was set to appear before a judge on Monday evening.

Prosecutors have called for her to be charged with terrorist conspiracy and kept in custody.

A 17-year-old friend of Lakdim’s was meanwhile released on Monday "due to the absence of incriminating evidence at this stage," prosecutors said.

President Emmanuel Macron will lead a national commemoration on Wednesday for hero policeman Arnaud Beltrame, who agreed to swap himself for a hostage inside the supermarket but was then killed by Lakdim who slit his throat.

The fact that Lakdim was on France’s terror watchlist has led to accusations from the right and far-right that Macron’s government is too soft on Islamists, while far-right leader Marine Le Pen has called for the interior minister to resign.

The government hit back at the criticism Tuesday.

"Those who say ignorantly that this attack could have been avoided, those who promise people zero risk -- I say to them, these people bear a heavy responsibility in speaking so casually," Prime Minister Edouard Philippe told parliament.

He rejected proposals from rightwingers to impose an outright ban on ultraconservative Salafist Islam or "preemptively" detain the most radicalised Islamists.

France already has "a legal arsenal" to "understand, monitor and sanction" extremists, he said.

Experts point out that France has around 20,000 people suspected of being Islamic extremists and security forces have been successful in thwarting a series of attacks in recent years thanks in part to tough new anti-terror laws. — AFP