At least 21 Egyptian soldiers were killed and four others injured in an assault Saturday on a border patrol checkpoint in the western desert, the army's official spokesman announced.
The attack was the second to target the same military checkpoint in less than two months, after a similar assault June 1 left five soldiers dead.
The death toll is the highest in an attack against Egyptian army personnel since 25 police draftees were killed by Islamic militias in the Sinai peninsula last August.
No group has claimed responsibility for the attack as yet.
Army helicopters and special unit forces were immediately deployed in the area to hunt for attackers.