Militants in the Gaza Strip on Monday sent a mortar shell crashing into an open area in southern Israel, a day after a rare retaliatory air strike by Israeli forces, the army said.
Over the past two months, Gaza militants have begun firing sporadically across the border, ending a period of complete quiet that followed a full-scale Israeli aerial bombardment of the besieged Palestinian enclave in mid-November.
"A mortar shell struck an uninhabited area in the Eshkol region near the security fence between Israel and the Gaza Strip," an army spokeswoman said on Monday.
The incident came 24 hours after Israeli warplanes launched air strikes against the southern Gaza town of Khan Yunis, targeting weapons depots and a training site for the armed wing of Islamic Jihad, the military said.
The strikes, which came in response to rocket fire that hit open fields in southern Israel on Saturday, caused no casualties.
The Israeli authorities on Sunday also closed the Kerem Shalom goods crossing until further notice after Saturday's rocket attack, the defence ministry said, and restricted movement of people across the separate Erez crossing to "humanitarian cases".
Israel also cancelled visits that Gaza-based Palestinians were to make Monday to see family members held in Israeli jails, the Red Cross said.
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"The Israeli authorities told us yesterday that the planned visits of Palestinians from Gaza today were cancelled," ICRC spokeswoman Noora Kero told AFP.
"This affects 87 people who were supposed to travel to Israel."
A spokesman for the Israeli defence ministry said the visits were only cancelled because of the restrictions on the Erez crossing.
Prime Minister Benjamin Netanyahu told Sunday's weekly cabinet meeting that Israel would retaliate with great force against any rocket or missile fire.
"I want to make it clear that we will respond in a very offensive way against any rockets or missiles. We will take all necessary measures to ensure the security of Israelis... on all fronts," he said.
Israel had not carried out air raids on Gaza since early April, when it launched the first strikes since a truce brokered by Egypt in November ended a deadly eight-day conflict between the Jewish state and militants of Islamist movement Hamas, which rules the territory.
Netanyahu had last week vowed Israel would "exact a price" from the Gaza militants who fired missiles from Sinai at the southern resort city of Eilat on April 17.