Dozens of Muslims, including religious and army leaders, packed an Egyptian mosque for Friday prayers a week after jihadist gunmen massacred more than 300 people in the house of worship.

The mosque in Rawda village in North Sinai had been cleaned and renovated following the massacre by suspected Islamic State group gunmen in time for the weekly Friday prayer.

The head of Egypt's Second Field Army Khaled Mogawer, which is fighting IS in Sinai, could be seen in live footage aired on state television, sitting between the Grand Imam of Al-Azhar Ahmed al-Tayeb and the country's mufti Shawqi Allam.

The cleric who gave the prayer sermon tried to console the relatives of the victims, saying the dead were now in paradise, while condemning the attackers as the "brothers of devils".

"God wanted to take martyrs from you. Why, because God loves you," said the preacher Abdel Fattal al-Awari.

He recounted a saying by the Muslim Prophet Mohamed who, when asked whom God tests the most, responded: "The prophets, followed by the most exemplary."

Worshippers could be seen spilling out of the mosque into its plaza.

Tayeb later gave a speech in which he described the attackers as "cowardly cancer".

The Islamic State group in Egypt had killed hundreds of policemen and soldiers in attacks, and since last year more than 100 Christians in church bombings and shootings.

They had warned the mosque, which is associated with Sufis the jihadists call heretical, to stop holding mystical rites.

Witnesses and authorities had said the attackers were flying the Islamic State's black banner, but the group has yet to claim the massacre decried even by its supporters.

Analysts and officials say IS, responsible for atrocities around the world, many not claim responsibility following the backlash even from jihadists.