Egypt's army has sent special forces by air to the Sinai Peninsula to help existing troops and police forces destroy all terrorist cells in the peninsula, says an army spokesman.
Extra security measures have gone into effect at all security checkpoints across Sinai, said spokesman Brigadier Mohamed Samir.
A military checkpoint was hit by a car bomb in North Sinai on Friday, killing 28 Egyptian soldiers and injuring 30. Another attack hours later left three more soldiers dead.
A state of emergency was declared in Sinai soon after the attacks by President Abdel-Fattah El-Sisi.
A militant insurgency by jihadist groups in Sinai has intensified since the ouster of president Mohamed Morsi in 2013.
Hundreds of police officers and soldiers, as well as militants, have been killed in the violence.
No militant group has yet come forward to claim responsibility for Friday's attack, although Ansar Beit Al-Maqdis, a jihadist group active in Sinai, has claimed responsibility for many similar assaults.