At least 10 Egyptian soldiers are reported killed and several more wounded in a car bomb attack near the North Sinai city of el-Arish.
Al-Masri al-Youm newspaper said a convoy of buses carrying infantry soldiers was hit by a roadside bomb as it moved through the Kharouba area.
The death toll was likely to rise, a security source said.
Attacks on security forces in the Sinai have increased since Islamist President Mohammed Morsi was ousted in July.
No group has admitted carrying out Wednesday's bombing, but the peninsula has grown increasingly unstable in recent years, triggered by the fall of President Hosni Mubarak.
His overthrow in February 2011 left the northern Sinai prone to groups of jihadists, some with links to the Gaza Strip.
In September security forces launched an offensive against Islamist militants in the Sinai, but have suffered a spate of deadly bombings.
