A man has been arrested in France over an alleged plot to attack churches, after he apparently shot himself by accident and called an ambulance.

Electronics student Sid Ahmed Ghlam, a 24-year-old Algerian national, is also suspected of the murder of a 32-year-old woman.

Prosecutor Francois Molins told journalists Ghlam’s plans were exposed purely by chance after he called an ambulance saying he had been shot during an armed robbery at his Paris home.

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When police arrived at the scene of his apparent accidental shooting, they followed a trail of blood to his car.

They found weapons and bullet-proof vests in the car and at his home, as well as printed material on Al Qaeda and the Islamic State.

“Detailed documents that were found established beyond doubt that the individual was planning an imminent attack, probably on one or two churches,” interior minister Bernard Cazeneuve said.

He said Ghlam had previously come to the attention of the French authorities as possibly wanting to go to Syria.

Police had made checks on him in 2014 and 2015 without finding anything that would warrant further investigation.

Mr Molins said a search of Ghlam’s phones and laptops “revealed that he was in touch with another person, who could be in Syria, with whom he was discussing ways to carry out an attack and who had specifically asked him to target a church”.

A source close to the investigation said Ghlam appeared to have carefully calculated how long it would take police to respond.

Several members of his entourage and family have since been detained, some of whom sympathise with radical Islam, sources close to the investigation said.

On Wednesday, his 25-year-old girlfriend was also taken in for questioning.

French PM reminds citizens of ‘unprecedented terrorist threat’

French prime minister Manuel Valls reiterated government warnings that the country was facing an “unprecedented terrorist threat”.

“To target a church is to target a symbol of France, the very essence of France,” said Mr Valls after visiting two churches in Villejuif outside Paris that were the apparent focus of the foiled attack.

“Terrorists are targeting France to divide us and our response must of course be to protect citizens but also to rally together, unite and to be hugely determined faced with this terrorist threat.”

Ghlam’s arrest came more than three months after Islamic extremists went on a three-day killing spree in and around Paris, leaving 17 people dead.

The January attacks on Charlie Hebdo magazine, a policewoman and a Jewish supermarket sent shockwaves around the world, and prompted several reforms in France including controversial new spy laws.

The new laws are currently being debated in parliament.

The French capital is still on maximum alert following the January attacks.

Hundreds of French nationals have left France to join jihadist ranks in Iraq and Syria, where they represent almost half the number of European fighters present, according to a report released this month.

Authorities are concerned they will come back and commit attacks in France.

During their investigations police discovered one of Ghlam’s guns had been used to shoot young mother Aurelie Chatelain, who was found dead in Villejuif on Sunday.

Ghlam’s link to the woman was not clear.