Palestinian sources said Hamas and Islamic Jihad squads have successfully used timers to launch Kassam-class, short-range missiles and rockets against targets in Israel, adopting a tactic of the Iranian-sponsored Hizbullah.

The sources said the use of timers was meant to avoid Israeli air strikes against Palestinian gunners.

"The timers were introduced several months ago and have proven effective," a source said. "We expect that most of the Kassam attacks against Israel will be operated by timers."

The Israeli military has captured some of the timers used on the Kassams. On July 6, units of the army's elite Givati Brigade raided the northern Gaza Strip and captured eight rocket launchers.

All the launchers were connected to timers, actually stopwatches. The launchers had been erected outside the town of Bet Hanoun.

The timers have been employed amid intensified Israeli military operations in the Gaza Strip. The military has sought to establish a closed border zone at least one kilometer inside the Gaza Strip.