World Bulletin/News Desk

Gunmen killed 21 Egyptian military border guards near the frontier with Libya on Saturday, highlighting a growing threat from an area that authorities say has become a haven for militants seeking to topple the Cairo government.

Security officials said the assailants were smugglers. But the army spokesman said on his Facebook page that "terrorists" were behind the attack.

He said a weapons storage facility was blown up by a rocket-propelled grenade in an exchange of fire, killing the soldiers and wounding four others.

The attack took place in Wadi al-Gadid governorate, which borders both Sudan and Libya. Two smugglers were killed in clashes with the guards, security officials said.

Security officials say those militants pay smugglers to transport weapons, including machineguns and rocket-propelled grenades, to comrades in Egypt.

Tribal smugglers told Reuters they charge up to one million Egyptian pounds ($140,000) to move weapons in four-by-four vehicles along desert routes.

Five border guards were killed in a similar attack in the same area a few months ago.

Egypt considered launching a cross-border offensive several months ago in a bid to crush the militants, according to two Egyptian national security officials.