A cousin of one of the two men believed to have killed a French priest in a church last week has been arrested.

Abdel-Malik Nabil Petitjean, aged 19, was shot dead by police after the attack.

Now the Paris prosecutor’s office says his cousin, identified as Farid K, aged 30, has been placed in preventive detention.

The French-born man was put under formal investigation on suspicion of terrorist association with a view to perpetrating a crime, the prosecutor’s office said on Sunday.

Another man, named as Jean-Philippe Steven J, 20, was also put under formal investigation for attempting to travel to Syria in June with Petitjean.

He was also sent to preventive detention.

Knife-wielding attackers interrupted a church service in Saint-Etienne-du-Rouvray, western France, on July 26, forced 85-year-old Roman Catholic priest Father Jacques Hamel to his knees and slit his throat.

Police identified the other attacker as19-year-old local man Adel Kermiche.

Investigators are still trying to determine how the two men met.