Israel has complained to the United Nations about a barrage of rockets and mortar shells fired at it from the Gaza Strip over the past days.
On Tuesday morning, one rocket landed outside a kindergarten in a kibbutz (agricultural commune) near the southern Israeli city of Ashkelon, injuring a 14-year-old girl as parents were dropping off their children for school, DPA reported.
In letters to Security Council President Susan Rice and UN Secretary General Ban Ki-moon that were released to the media on Wednesday, Israel's UN ambassador, Meron Reuben, demanded the international body "send a clear and resolute message that these attacks are unacceptable."
He also demanded the Security Council devote more attention to arms smuggling into Gaza, which, he said, "continues to fuel violence and instability in our region."
A Foreign Ministry statement Tuesday said Israel holds Hamas, the de facto authority in Gaza, "completely responsible for all of these incidents, carried out in clear violation of international law."
Palestinian militants have fired some 18 mortar shells and three rockets from Gaza at southern Israel over three days, apparently to avenge the killing by Israel of five Palestinian gunmen in a Saturday airstrike against a militant cell.
Those gunmen, in turn, were attempting to launch more rockets into Israeli territory.
Four Palestinians were also wounded in retaliatory airstrikes on Gaza late Monday night and Tuesday as Israel responded to the initial launches out of Gaza.
Saturday's airstrike upon Gaza was the deadliest in months.
Israel's military chief of Staff, Gabi Ashkenazi, Tuesday described the situation in the Strip as "frail and volatile," telling a parliamentary committee there was no guarantee it would not deteriorate further.
Lieutenant General Ashkenazi also revealed that militants in the Gaza Strip had earlier this month fired a Kornet anti-tank missile at an Israeli tank.
The missile had penetrated the tank's outer armour, but had failed to explode. There were no injuries.
It was the first time such a weapon had been fired from the Gaza Strip.
The missile, which Ashkenazi described as "one of the most dangerous in the world," had been used by Lebanon's Hezbollah organization in the 2006 war between Israel and the Iranian-backed guerrillas.
Since Israel's three-week war against Hamas in the winter of 2008- 2009, the two sides have largely abided by an unwritten truce. But violence has flared up from time to time, with sporadic rocket and mortar attacks and Israeli retaliatory airstrikes.
Some 1,400 Palestinians, many of them civilians, were killed during the Israeli offensive, in massive bombardments from the air, land and sea on Hamas targets in the densely populated strip, as well as in ground fighting.
The offensive aimed to curb the rocket and mortar attacks from Gaza. Throughout 2010, Palestinian militants fired more than 200 projectiles at Israel, compared to more than 3,000 in the months building up to the Gaza war.