Eleven people were killed and seventeen were wounded by two explosions in the northern Sinai Peninsula in the town of Rafah on Wednesday morning, Israel Radio reported.
Most of the casualties were Egyptian soldiers and Ansar Bayt al-Maqdis a group affiliated with al-Qaida took responsibility for the attacks, according to the report.
One of the explosions occurred near an Egyptian military intelligence center when a car bomb exploded and a few minutes later another military outpost was attacked.
An earlier report by state TV said rocket-propelled grenades had been fired at a military facility in Sinai. It was not clear if this was a separate attack. Witnesses said they heard explosions and saw clashes between militants and troops in the area.
Ansar Bayt al-Maqdis said it carried out the attacks in response to the Egyptian army's recent assaults on militants in the lawless peninsula. Last week the group claimed responsibility on for Thursday's suicide bombing aimed at Interior Minister Mohamed Ibrahim.
Following the group's admission Egypt said it tightened control of crossings from the Sinai peninsula and continued assaults on militants.
Earlier, on Saturday, the Egyptian military launched a major assault on militants in North Sinai, killing or wounding at least 30 people in clashes close to the Palestinian Gaza Strip.
The assault continued on Monday, with security forces killing nine and arresting 10 "armed elements" near Sinai cities of Sheikh Zuweid and Rafah.
The area of the northern Sinai close to Israel and the Gaza Strip, has seen a sharp rise in militant attacks since the army ousted Islamist president Mohamed Morsi in July.