The Sinai-based armed group was founded after the July coup, and has mostly targeted military men and police forces.
Egyptian President Abdel Fattah al-Sisi has cut short a visit to Ethiopia for an African Union summit, following a wave of deadly attacks in the Sinai Peninsula claimed by a group that pledges allegiance to the Islamic State of Iraq and the Levant (ISIL).
The president’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.
His decision comes as two children were killed in clashes between the army and fighters in Sinai hours after at least 45 people, mostly soldiers, died in violence there, security officials said.
Fighters fired a barrage of rockets and set off a car bomb in a series of attacks in North Sinai province in some of the worst anti-government violence in months, according to security officials.
Ansar Beit al-Maqdis that now calls itself the Sinai Province, said it was retaliating against a government crackdown on supporters of former President Mohamed Morsi.
It claimed responsibility for the attacks that struck the provincial capital of El-Arish, the nearby town of Sheik Zuwayid and the town of Rafah bordering the Gaza Strip.
The armed group claimed via a Twitter account that it “executed extensive, simultaneous attacks in the cities of El-Arish, Sheikh Zuweid and Rafah”.
A military base, a nearby police headquarters, a residential complex for army and police officers and an army checkpoint were targeted in El-Arish in the biggest such attack since October.
“Terrorist elements have attacked several police and army headquarters and facilities using explosive-laden vehicles and rockets,” the military said.
Security officials said fighters first fired rockets at the El-Arish police headquarters and the military base, which was followed by the car bomb.
Minutes later a barrage of rockets struck the nearby housing complex.
In a separate attack, an officer was killed when a rocket struck an army checkpoint in the town of Rafah, on the border with Gaza.
Overall, officials said at least 62 people were wounded in the attacks in North Sinai.
In a separate incident a police officer was killed when struck by a bomb in the canal city of Suez.
The El-Arish attack was the deadliest since an October 24 assault, which was also near El-Arish, when fighters killed 30 soldiers and wounded scores more.
That attack prompted the authorities to build a buffer zone along the Gaza border to prevent fighters infiltrating from the Palestinian territory.
Armed groups have regularly attacked security forces in the Sinai Peninsula since President Morsi was toppled by then army chief and now President Abdel Fattah el-Sisi in July 2013.