Egypt's leading ultraconservative Islamist party says gunmen on a motorcycle have killed their party's secretary, who was a parliamentary candidate in the restive northern Sinai city of el-Arish.

The Salafi Al-Nour Party says in a statement that Mostafa Abdel-Rahman was shot dead Saturday in front of his home as he headed out to a mosque for afternoon prayers.

No group immediately claimed responsibility for the killing.

Al-Nour supported the 2013 military overthrow of Islamist President Mohammed Morsi, who hailed from the rival Muslim Brotherhood group.

Egypt has been battling a long-running Islamic insurgency in the Sinai peninsula, which escalated following 2013 with an Islamic State affiliate and other militant groups carrying out attacks, mainly targeting security forces.