GAZA CITY, Palestinian Territories (AFP) - Israeli air planes struck targets in the southern Gaza Strip, witnesses and the army said early on Saturday, hours after a rocket from the Palestinian enclave hit the Jewish state.

A spokesman for Gaza's health ministry said there were no casualties in the attack, the first air strike by Israel on the Palestinian enclave since the summer truce that ended the deadly 50-day war between the sides.

The Israeli army confirmed the strike, which it said "targeted a Hamas terror infrastructure site".

Military spokesman Lieutenant Colonel Peter Lerner said in a statement that the "Hamas terrorist organisation is responsible and accountable for today's attack against Israel."

On Friday, a rocket fired from Gaza hit an open field in southern Israel, Israeli police said, causing no casualties or damage.

The Islamist militant movement, which has de facto rule over Gaza, did not assume responsibility for the attack, the third such incident since the end of the fighting between the sides nearly four months ago.

Hamas and Israel agreed a ceasefire on August 26, brokered by Egypt, ending 50 days of war which resulted in the deaths of 2,140 Palestinians and 73 Israelis, most of them soldiers.