A heavily armed Islamic extremist planning an imminent attack on one or more churches has been arrested in Paris, say the French authorities.

The man (24) is also accused of killing a young mother shortly before his arrest, according to Interior Minister Bernard Cazeneuve.

The Algerian suspect was detained after he apparently shot himself by accident and called for an ambulance, said a security official.

Police called to the scene found a trail of blood leading to his car, with loaded guns and notes about potential targets inside.

A search of the man's apartment in the south-east of the French capital led to the discovery of more weapons, as well as evidence of links to Islamic extremism.

But the official said there was no sign the suspect had direct ties to any organised groups.

The computer science student is said to have lived in France for several years and had been "flagged" by the security services last year.

The dead woman, Aurelie Chatelain (32), who had been visiting Paris for a work training session, was found shot in her car on Sunday morning.

The authorities believe she was killed at random.

France has been on heightened alert since the deadly attacks in January on the satirical newspaper Charlie Hebdo and a kosher supermarket in which 20 people were killed, including the three gunmen.