Israeli security forces discovered on Tuesday a potentially lethal bomb on the border with Egypt during an operation to foil smuggling from the Sinai desert, the army said.
"A powerful explosive device was uncovered in joint Israel Defense Forces-Israel police activity intended to thwart smuggling attempts along the Israel-Egypt border," a statement said.
"A smuggling attempt was identified, and the force that operated to stop the smuggling identified a man hurling a suspicious bag and escaping from the scene," it said, describing the bag as a black rucksack.
"The bag contained a powerful explosive device."
The incident occurred toward the northern end of the 240-kilometer (150-mile) Israeli-Egyptian frontier, a few kilometers from the Gaza border.
It was not immediately clear what happened to the man seen throwing the bag.
The head of the army's special operations engineering unit, identified only as "Major M," said the device contained "several kilograms" of explosive attached to what appeared to be a mobile phone detonator.
"It was either an improvised anti-personnel device or an explosives belt with an apparent cellular detonation system," he told reporters, saying army sappers had blown up the bag and its contents.
"In our estimation such a device used against a built-up area or a shopping mall or a bus would have caused heavy damage and multiple casualties."
He could not say what the device was intended for or who had brought it to the border but noted there was "widespread activity by smugglers and illegal migrants" in the area.
The border area is a paradise for Bedouin smugglers, with the Israeli authorities often seizing drugs, cigarettes and telecommunications equipment as well as weapons and explosives heading for the Gaza Strip.
It has also provided a springboard for militant attacks.
Last August, gunmen infiltrated southern Israel from Sinai and launched a coordinated series of ambushes on vehicles on a border road north of the Red Sea resort of Eilat. Eight Israelis were killed.
Israel currently is building a giant steel security barrier along the frontier, which is due to be completed by the end of this year.