Church attacker Abdel Petitjean threatened France in new video

Dressed in a striped t-shirt, he speaks mostly in French but uses some Arabic phrases, and appears to be filming in a home

A jihadist involved in the brutal killing of an elderly priest pledged to attack France in a newly released video, as Catholic bishops called for a day of prayer in a nation shaken by the latest assault.

The assailant has been named as 19-year-old Abdel Malik Petitjean, who was listed in June on France's "Fiche S" system of people posing a potential threat to national security after he tried to reach Syria from Turkey.

Petitjean threatened France and directly addressed President Francois Hollande and Prime Minister Manuel Valls in the footage released by the Islamic State-linked Amaq news agency.

Dressed in a striped t-shirt, Petitjean speaks mostly in French but uses some Arabic phrases, and appears to be filming in a home.

Petitjean, whose face was disfigured when he was shot dead by police, had been harder to identify than his accomplice Adel Kermiche, also 19. Investigators confirmed his identity after a DNA match with his mother.

The pair pledged allegiance to the Islamic State group in a video made before they stormed a church in the Normandy town of Saint-Etienne-du-Rouvray on Tuesday and slit the throat of 86-year-old priest Jacques Hamel at the altar.

The president of the Conference of Bishops in France Georges Pontier called on all Catholics in the country to observe a day of national prayers and fasting on Friday "for our country and for peace in the world".

"We have various sentiments at this time. We know well that the only brotherhood, in our country, is the voice that leads to lasting peace. Let's build it together," he said in a statement earlier this week.

Hamel's funeral will be held in the Gothic cathedral of nearby Rouen next Tuesday.

The church attack came as the government was already facing a firestorm of criticism over alleged security failings after the Bastille Day truck massacre in Nice that left 84 people dead two weeks ago.

A brief show of political unity at a mass attended by different faiths in Paris on Wednesday quickly dissolved as Prime Minister Manuel Valls and Interior Minister Bernard Cazeneuve faced fresh calls to resign.

"Even if the government is not responsible for the wave of terrorism, it is guilty of not having done everything to stop it," Laurent Wauqiez, the deputy leader of the right-wing Republicans party, said in an interview.