A senior military officer and one soldier were killed on Saturday by a roadside explosion in Egypt's North Sinai where the government faces an Islamic State-led insurgency, security sources told Reuters.
Hundreds of soldiers and police have been killed in the insurgency and there have also been attacks in Cairo and other cities.
Militant groups appear to be stepping up attacks with the emergence of a new group calling itself the Revolution Brigade which claimed responsibility for the killing of a brigadier general, a commander in North Sinai, outside his home on the outskirts of Cairo last week.
That attack came just one week after Islamic State guerrillas ambushed a military checkpoint killing 12 Egyptian soldiers in the town of Bir al-Abd, the first major attack in the central Sinai area, which had so far escaped the militant Islamists' campaign.
Military and police sources who did not wish to be identified told Reuters that Saturday's explosion was a targeted attack on Colonel Rami Hassanein, who was killed while travelling in an armoured vehicle just outside North Sinai's Sheikh Zuweid.
One other soldier was killed and three others were injured in the attack, the sources said.
Egypt's military has not released a statement on the incident and was not available for comment.
An 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 militant group staging the insurgency pledged allegiance to Islamic State in 2014 and adopted the name Sinai Province.