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.
Four gunmen were killed in the latest gun battle in the governate of El Wadi el Gedeed, state television reported.
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.
The army's official spokesman, Brig. Mohamed Samir, said the assault took place when militants opened fire using rocket-propelled grenades at the checkpoint on the Farafra Oasis Road near Egypt's borders with Libya.
"One grenade targeted a nearby ammunition warehouse," which resulted in the high number of deaths, Samir said on the army’s Facebook page. Troops managed to defuse bombs attached to two vehicles left behind by the attackers in the scene, he said.
No group has claimed responsibility for the attack as yet.
While the state newspaper Ahram's website quoted a security source as saying that a group of smugglers initiated the attack, independent newspapers reported that the attackers’ four-wheel-drive vehicles carried Al Qaeda flags.
Army helicopters and special unit forces were immediately deployed in the area to hunt for attackers.
Egypt's border with Libya has seen continuous arms smuggling attempts since the ouster of Libyan leader Moammar Kadafi in 2011.
Hassan is a special correspondent.