PARIS (AFP) - French investigators probing an attack on a Catholic church believe one of the assailants is a young man who was wanted by anti-terrorism police, sources close to the investigation said.

Only one of the two attackers, who stormed into a church in the northern town of Saint-Etienne-du-Rouvray during morning mass on Tuesday (July 26) and slit the 86-year-old priest's throat at the altar, has been officially identified.

However, during a raid on the home of one of the attackers, 19-year-old Adel Kermiche, police found an identity card belonging to Abdel Malik P, also 19.

"Several elements lead us to believe he is the second attacker," said one of the sources close to the investigation.

Abdel Malik P., who is from the Savoie region, has never been convicted of a crime in France so his DNA and fingerprints are not available to speed up the identification process.

Sources say that after being gunned down by police, the second attacker's face was too disfigured to allow him to be clearly identified.

However, the sources said that France's anti-terrorism police unit UCLAT sent out a note four days before the attack - saying it had received "reliable" information about a person "about to carry out an attack on national territory".

The note came with a photograph which "strongly resembles" Abdel Malik P.

Kermiche was rapidly identified as he had been under house arrest, and was wearing a monitoring bracelet, after being arrested in Turkey for trying to reach Syria.

The attack was claimed by the Islamic State in Iraq and Syria. But it was not clear if the two men were inspired from afar by militant propoganda, or were following direct orders.