Washington: The US has expressed concern over rocket attacks by Gaza militants in southern Israel."We are deeply concerned by the renewal of violence in southern Israel," State Department spokeswoman Victoria Nuland said in a statement on Saturday.

"We condemn in the strongest terms the rocket fire from Gaza by terrorists into southern Israel in recent days, which has dramatically and dangerously escalated in the past day," she said.

Fourteen militants killed and over 20 Palestinians injured as Israeli jets struck back. The majority of the dead are members of the military wing of the Islamic Jihad movement, as reported.

The violence is the worst since August 2011, when 25 Palestinians were killed in a wave of violence after Israel killed Kamal al-Nairab, top commander of the pro-Hamas Popular Resistance Committees.

Israeli Prime Minister Benjamin Netanyahu said on Saturday that Israel would continue to strike any group trying to attack Israeli citizens and would acquire more Iron Dome systems to shoot down incoming rockets.