A rocket fired by Palestinian militants in the Gaza Strip struck the western Negev on Friday, for the fifth time in 24 hours.
Israel Air Force air craft struck at least six targets in the Gaza Strip befire daFriday a day after a rocket fired from the Palestinian enclave killed a Thai worker in southern Israel, Hamas security officials and witnesses said.
Two civilians were injured in one of three attacks on smuggling tunnels along the border with Egypt. The other targets included two open areas in Khan Younis and a metal foundry near Gaza City.
The Israeli military had no immediate comment.
Vice Premier Silvan Shalom had said on Thursday Israel would make a strong response to what was the first deadly rocket fire from Hamas-ruled Gaza at Israel in more than a year.
Israel also sent a letter of complaint to UN Secretary General Ban Ki-moon, who is due to visit Israel at the weekend, and the UN Security Council.
Israel's UN Ambassador Gabriela Shalev urged Ban to call for the release of Israeli soldier Gilad Shalit, captured by Gaza militants in 2006. Hamas has demanded Israel free hundreds of the thousands of militants in its jails in exchange for the soldier.
A previously unknown group, Ansar al-Sunna, believed to share the hardline ideology of al Qaeda, claimed responsibility for the rocket fire at Israel, as well as the Al-Aqsa Martrys Brigades, a wing of the mainstream Fatah movement.
Hamas Islamists, who took control of the Gaza Strip in 2007, had beenurging other militant groups not to strike Israel, voicing concern about possible Israeli retaliation.
Palestinian militants in Gaza have carried out sporadic rocket and mortar bomb attacks on Israel since the end of a three-week Gaza war in January 2009, usually without causing any Casualties.
Israel has responded to periodic rocket fire from Gaza since a war last year with air strikes.
Often these are tempered to avoid casualties as a signal to Hamas Israel holds it responsible while aware it was not behind the rocket fire, or to avert the appearance of disrupting U.S.-backed diplomacy in the region.
The latest air strikes took place the day of a meeting of Quartet Middle East power mediators in Moscow and just ahead of a planned visit by U.S. envoy George Mitchell, who is seeking to relaunch moribund peace talks in the region.
More than 1,400 Palestinians, including hundreds of civilians, were killed in that offensive, launched with the declared aim of curbing rocket attacks. Thirteen Israelis, among them three civilians, were killed.