French president attends memorial for IS-slain priest

French President Emmanuel Macron has spoken at an emotionally-charged mass to mark one year since the killing of a local French priest by two 19-year-old Islamic extremists.

Wednesday's ceremony took place outside the Saint-Etienne-du-Rouvray church, where the men slit the throat of Father Jacques Hamel, 85, as he celebrated morning Mass.

Calling him a "martyr" in an impassioned speech, Macron said "Hamel's smile has become a reminder of resistance in the face of bigotry."

Macron said the two jihadis "have failed" in sowing a thirst for vengeance among French Catholics.

Rouen Archbishop Dominique Lebrun led the service, saying that "though he is dead, Father Jacques Hamel is still alive ... hate has not triumphed, and it will never triumph."

The Islamic State group claimed responsibility for the attack.