Israel's top military chief has warned Gaza militants not to "test" Israel's strength as troops and police remained on high alert on Wednesday over warnings of a planned attack from Sinai.
"Hamas and other terrorist organisations in Gaza must know that they are wrong to test our strength and that any attempt to harm the citizens of Israel will result in a severe response," chief of staff Benny Gantz said in remarks released by the army.
The military two days earlier raised the level of alert on the Israel-Egypt border and around Gaza following specific intelligence warnings that militants were planning a fresh attack on south Israel along the lines of a series of deadly ambushes on August 18.
"The defence establishment has received a warning that a terror cell in Sinai, comprised of more than 10 terrorists, is going to try and carry out an attack," Home Front Defence Minister Matan Vilnai told Israeli reporters on Tuesday, indicating Islamic Jihad was involved.
Avi Dichter, an Israeli MP and former head of the Shin Bet internal security service, said attacking Israel from Sinai was a way for Gaza militants to hide their involvement in attacks which could complicate the Palestinian bid to seek UN membership next month.
"The moment the terror organisations in the strip understood that direct terror from Gaza makes the campaign they're planning in September at UN very difficult, the alternative is a bypass... from Gaza to Sinai and from Sinai into Israel," he told Israeli public radio.
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Although Gaza's Hamas rulers are not involved in the bid, they are keen to see it succeed and unlikely to engage in any overt attack on Israel that would harm the initiative, he said.
On August 18, a group of gunmen crossed the Egyptian border and killed eight Israelis on a desert road which flanks the frontier just north of the Red Sea resort town of Eilat.
Israel blamed the Gaza-based Popular Resistance Committees and hit back at them, sparking a week of air strikes and retaliatory cross-border rocket attacks which left 27 Palestinians and an Israeli dead.
A truce agreement signed at the end of last week appears to be holding, but Israeli press reports speculated that Gazan groups were planning fresh attacks to avenge the deaths of those killed in the Israeli strikes.
Two roads which skirt the Egyptian border have been closed to all civilian traffic, and the military was also preparing for the possibility of rocket fire from Sinai towards the Red Sea resort of Eilat, Haaretz newspaper reported.
In a separate development, the navy on Tuesday deployed two missile boats just outside Eilat in what the military said was part of a "routine exercise."
Israeli press reports said it was unlikely the boats' deployment was linked to the high state of alert in the south.
But it came as Tehran's top naval commander said Iran had dispatched a submarine and a warship to the Red Sea on a "patrol mission," state television reported.