Egyptian President Abdel Fattah al-Sisi cut short a visit to Ethiopia for an African Union summit on Friday, following a wave of deadly attacks in the Sinai Peninsula claimed by Islamic State's Egyptian wing.
Sisi's office said in a statement that Sisi, who was scheduled to address the summit, would head back to Cairo after the opening session on Friday morning.
At least 26 security personnel were killed late on Thursday in four separate attacks in North Sinai, in some of the worst anti-government violence in months.
Egypt is fighting an Islamist insurgency based in the Sinai. Hundreds of members of the security forces have been killed since the army ousted president Mohamed Mursi of the Muslim Brotherhood in July 2013 after mass protests against his rule.
The Brotherhood denies any links to the insurgents but the government makes no distinction between them.
The most active militant group, Ansar Bayt al-Maqdis, changed its name to Sinai Province last year when it swore allegiance to Islamic State, the hardline Sunni militant group that has seized swathes of Iraq and Syria, drawing U.S.-led air strikes.
The attacks in the peninsula, which borders Israel and the Gaza Strip, were the deadliest since 33 security personnel were killed in two attacks in October.
The week had already been a bloody one for the Arab world's most populous nation. More than 25 people were killed at the weekend when security forces fired at protesters angered by what many perceive as a police state.
After the October attack, Egypt declared a state of emergency in the area where Sinai borders Gaza and accelerated plans to create a 500 metre (550 yard) deep buffer strip by clearing houses and trees and destroying subterranean tunnels that it says are used to smuggle arms into Sinai. Critics say the government is stoking resentment against already marginalized communities.
A crackdown on protests appears unlikely to provoke widespread unrest, though, as most Egyptians support the government's fight against Islamist militants and crave stability.
Sisi, the former army chief who toppled Mursi, says Egypt is fighting a war on terrorism and has the support of Western and Gulf Arab allies.
