Wednesday’s predawn raid is part of a major operation launched earlier this week to root out the militants in Sinai. The militants have taken advantage of a security vacuum following President Hosni Mubarak’s ouster in February, launching brazen attacks on police patrols and a key pipeline that carries natural gas to Jordan and Israel.

The official said the raid uncovered explosive belts, land mines and hundreds of automatic weapons. He spoke on condition of anonymity because he was not authorized to talk to the media.

On Tuesday, the army arrested four gunmen in the Sinai Peninsula as they prepared to detonate a device near the pipeline to Israel near El-Arish, a security source said.

"Security guards near the terminal informed the army of suspicious movements," the source said. "Members of the armed forces, backed by armored cars, immediately headed to the region and managed to encircle the four."