One of the two attackers who killed a priest in a church in France has been identified as Adel Kermich.

85-year-old Father Jacques Hamel was killed by two men armed with knives who slit his throat in a church in the small Normandy town of Saint-Etienne-du-Rouvray.

The attackers took hostages during morning mass before being shot dead by French police outside the church.

Several other people were injured, including one who is currently fighting for their life in hospital.

The priest was forced to kneel by two men armed with knives before they slit his throat, according to a nun who witnessed the deadly attack.

The pair also filmed the murder and gave a "sermon around the altar in Arabic".

The attack has been claimed by Islamic State, which said the men were its "soldiers".

Saint-Etienne-du-Rouvray in Normandy, France | Image: Francois Mori / AP/Press Association Images

Who were the Normandy attackers?

Sky sources have confirmed one of the assailants was 19-year-old Adel Kermiche, who lived in the town.

He made two attempts at travelling to Syria from Turkey and was known to the security services.

After being sent back to France in 2015 he was jailed before being released this March when he reportedly had to wear an electronic tag allowing police to locate him at all times.

When he was not yet 18, he was detained in Germany while on his way to Syria, a source told the AFP news agency.

He then tried to get to the war-ravaged country again by making his way through Switzerland before being detained.

The man was sent back to France last year, where he was charged and jailed for associating with criminals with terror links.

A witness also said he had threatened to attack a church.

Meanwhile, a suspect, believed to be 17-years-old and whose brother reportedly went to Syria last year, has been arrested as part of the church investigation.

IS has previously encouraged its followers to attack Christian places of worship.

Last summer, it said to target "traffic areas, such as tourist sites, supermarkets, synagogues, churches, Masonic Lodges, the permanence of political parties. The goal is to instill fear in their heart".

It is not believed to be the first time that jihadists have planned to target places of worship in France.

In April 2015, Algerian national Sid Ahmed Ghlam was arrested in Paris on suspicion of planning to attack churches in the capital.

He was detained after he apparently shot himself by accident and called an ambulance.