Thousands of mourners were expected at Rouen cathedral for the funeral of the French priest killed while celebrating mass a week ago.
The interior minister, Bernard Cazeneuve, will attend the funeral of Father Jacques Hamel, which is taking place amid tight security.
Father Hamel, 85, was among six people taken hostage when two men who had pledged allegiance to Islamic State stormed the church at Saint-Étienne-du-Rouvray.
The attackers, Adel Kermiche and Abdel Malik Petitjean, both 19, forced the priest to kneel before slitting his throat, then stabbed one of his elderly parishioners. Sister Danielle, one of three nuns present, managed to escape and raise the alarm. The pair were shot dead as they left the church.
Kermiche and Petitjean, who are thought to have met for the first time only days before the attack after making contact on the encrypted messaging app Telegram, had both tried to join Isis in Syria. Kermiche had been released from prison awaiting trial for two attempts to join the jihadis, and was wearing an electronic bracelet at the time of the attack.
The funeral mass, which starts at 2pm (1pm BST), will be led by the Archbishop of Rouen, Dominique Lebrun. About 2,000 people are expected inside the cathedral and the ceremony will be relayed to a screen outside for hundreds more. Afterwards, Father Hamel will be buried in a private family ceremony.
Philippe Maheut, the vicar general of the Rouen diocese, said the priest’s coffin would enter through the “door of forgiveness and mercy”.
“Father Hamel’s stole, the sign of his life as a priest, will be put on the cross of Christ, in the choir of the cathedral as a sign that, like Jesus, he gave his life in a way that was not chosen, but was real,” Maheut told journalists.
Mohamed Karabila, imam of the mosque at Saint-Étienne-du-Rouvray, will attend the funeral.
Bachar r El Sayadi, president of the Rouen Muslim Union, said: “French Muslims share the same happiness and sadness as other citizens of the country. For that reason it’s important that we are all together.” He appealed for a special collection for the Hamel family.
Saint-Étienne-du-Rouvray’s Muslims have opposed suggestions that Kermiche could be buried in the town where he killed the local priest.
“Given that he’s a terrorist who has done us much wrong, he doesn’t deserve any respect,” Karabila told Europe 1 radio. “Having said that, his remains have to be buried somewhere. There will be no official (mosque) representative and no prayer at the mosque.”
The town authorities at Saint-Étienne-du-Rouvray have not decided whether to allow the terrorist’s burial in their district.
Three men are in the custody of anti-terrorist police and being questioned about their connection to the attack. One of them, a 30-year-old cousin of Petitjean, is accused of “association with criminals in relation to an illegal terrorist organisation”.
The public prosecutor’s office said the suspect “was perfectly aware that his cousin’s violent plan of action was imminent”, adding that examination of the man’s phone and computer revealed that he knew “a lot more than he wanted to tell police”.
A 17-year-old who tried to reach Syria with Kermich in 2015 before he was arrested in Switzerland and a 19-year-old are also under arrest.
On Monday evening, Brittany Ferries carried out an exercise with a view to introducing armed sea marshals on board French cross-Channel vessels. No firm plan has been announced to make trained military personnel part of the crew.