Egyptian jets bombed Islamist militant targets for three hours on Saturday, one day after Islamic State guerrillas killed 12 soldiers in North Sinai province, the armed forces said in a statement.
Islamic State claimed responsibility on Friday for the attack on a checkpoint 40 km (25 miles) from the town of Bir al-Abd. It was the first major attack in the central Sinai area, which had so far escaped the militants' insurgency.
"A targeted air strike, which lasted for three hours, resulted in the destruction of the areas ... that harbored terrorists, as well as locations for assembling weapons and ammunition," the statement said, adding that the operation was continuing.
Islamic State said in its statement on Friday that it had killed more than 20 soldiers while suffering no losses itself. The military said 15 attackers had been killed.
The Islamist insurgency in the rugged and thinly populated Sinai Peninsula gained pace after the military overthrew President Mohamed Mursi of the Muslim Brotherhood, Egypt's oldest Islamist movement, in mid-2013 following mass protests against his rule.
The group staging the insurgency pledged allegiance to Islamic State in 2014 and adopted the name Sinai Province. It is blamed for the killing of hundreds of soldiers and policemen, and has started to target Western targets within Egypt.