Islamic State's news agency on Wednesday posted a video of two men it said were those who attacked a church in France in which they pledged allegiance to the group's leader.

The video was posted by Amaq news agency a day after two men burst into the Catholic church in Normandy during a service, forced the priest to his knees and slit his throat.

The two men who identified themselves as Abu Omar and Abu Jalil el-Hanafy appeared in the one-minute video sitting on a staircase pledging loyalty to Abu Bakr al-Baghdadi, Islamic State's leader.

One of the two attackers has been named as 19-year-old Adel Kermiche, who was under close surveillance after two failed attempts to reach Syria last year, France's anti-terrorism prosecutor said on Wednesday

The second attacker remains unidentified. Police shot and killed both assailants as they emerged from the church.