The movement of Egyptian soldiers into the zone, a step Israel has described as temporary, has fuelled debate among Israelis over whether the fall of Egypt's President Hosni Mubarak would affect a peace treaty signed in 1979.
Under that pact, only a limited number of Egyptian police are permitted to patrol the border area. It also restricts the nature and size of Israeli forces on the other side of the frontier.
An Israeli official said Egyptian reinforcements "in the hundreds" had been brought in to help secure the zone, which saw rioting against the now-ousted Mubarak government as well as a suspicious fire at a gas pipeline facility on Feb. 5.
Egyptian gas supplies to East Mediterranean Gas Co (EMG) and its Israeli clients were expected to resume later this month, Ampal-American Israel Corp
Israel's Yedioth Ahronoth newspaper reported that 700 Egyptian soldiers had been deployed in the demilitarised zone in recent days, beefing up some 800 troops there since Jan. 30.
After the initial deployment, Israeli Defence Minister Ehud Barak said their movement into the area with Israel's blessing represented "a temporary situation, until the situation in Egypt has been stabilised".