Islamic Jihad's armed wing, the Al Quds Brigades, vowed Wednesday to fire rockets at cities deep inside Israel as it entered "a new phase" of resistance, a spokesman said.

"The Al Quds Brigade has entered a new phase of bombing targets which are further away, where thousands of Israelis live," Abu Ahmad told AFP.

"The stage of targeting Sderot and Ashkelon in southern Israel are behind us," he said, referring to a small Israeli town which lies very close to the border, and to a port city which lies 18 kilometres to the north.

"From now on, there are no more red lines for the resistance as long as the enemy doesn't respect UN conventions and keeps killing civilians," he said, vowing that the group would "respond in kind."

His remarks were made after the group fired two longer-range Grad rockets at the southern city of Beersheva, which lies 40 kilometres (25 miles) from Gaza, and much further away than the Israeli cities regularly targeted by Palestinian militants.

Overnight, Al Quds militants also fired a Grad at the port city of Ashdod, which lies about 30 kilometres (18 miles) north of Gaza.