Occupied Jerusalem: The Israeli air force hit the Gaza Strip early Sunday for the second time in three days after new rocket fire from the territory hit southern Israel, the military said.

It was the third time Israel had staged air strikes in Gaza in the past fortnight, with each raid following rocket fire on the Israeli south, raising fears of a new confrontation with Palestinian militants.

The Israeli government also ordered the closure until further notice of the Erez crossing for people and the Kerem Shalom crossing for goods.

Palestinian security sources and witnesses said the air force targeted a training site belonging to Hamas’s armed wing, the Ezz Al Deen Al Qassam Brigades, in the northern Beit Lahiya area.

The rocket fire on Saturday evening struck open ground near the southern Israeli port of Ashkelon, causing no casualties.

The same area was targeted by three rockets on Wednesday night, which also prompted retaliatory air strikes.

After that attack, the military deployed batteries of its Iron Dome air defence system around Ashkelon as a precaution, Israeli media reported on Friday.

The latest attack was claimed by a relatively-new group of Islamist extremists called the Supporters of Daesh in Jerusalem, which has claimed responsibility for all three instances of rocket fire in the past two weeks.

The first attack was on May 26.

The group is locked in power struggle with Hamas which is the de facto power in Gaza, with the Islamist movement’s security forces mounting a harsh crackdown on such fringe groups.

Last week, Hamas police shot dead a local Daesh leader during an arrest operation in Gaza City.

Since Israel’s deadly 50-day assault in and around Gaza last summer, there have been growing signs of internal unrest in the territory with a spate of bomb attacks targeting public buildings and officials as well as international organisations.