Egyptian security forces killed 55 militants in Sinai on the ninth day of an operation against Islamists in the area, the military said in a statement on Tuesday.
It was not possible to independently confirm the figure.
Egypt is battling an insurgency that gained pace after its military overthrew President Mohamed Morsi of the Muslim Brotherhood Islamist movement in mid-2013 in the wake of mass protests against his rule.
The insurgency, mounted by Islamic State's Egyptian affiliate, has killed hundreds of soldiers and police and has started to attack Western targets within the country. In Tuesday's fighting, two soldiers were killed, the military said.
The military had announced a new "comprehensive operation" carried out by joint units from the military and the police against militants in Sinai starting on Sept. 7.
Operation "Right of the Martyr" has so far resulted in the killing of 415 militants and the arrest of 320 people, according to daily military statements.
One officer and eight soldiers have been killed since the operation began.
President Abdel Fattah al-Sisi describes Islamist militancy as an existential threat to Egypt, the most populous Arab state and a close US ally.
Islamic State controls large parts of Iraq and Syria, has a presence in Libya and enjoys the support of militants in Egypt seeking to topple the Cairo government.