( Reuters ) - Israel on Wednesday launched its first major attacks in the Gaza Strip since Hamas took over the territory, killing at least four Palestinian fighters.
Israel carried out air strikes against rocket launch sites in northern Gaza after militants fired at least one makeshift rocket into southern Israel.
Islamic Jihad claimed responsibility for firing the rocket.
Earlier on Wednesday, Israeli troops killed four Palestinian fighters in the first such deadly skirmish in the coastal enclave since Hamas Islamist militias overran President Mahmoud Abbas's Fatah faction and seized control of the territory a week ago.
Officials said two Hamas fighters and two other militants were killed in the clash near the Kissufim border crossing. Israeli tanks and troops had pushed into the coastal enclave in a hunt for wanted Palestinian militants, the army said.
Two other Palestinian guerrillas, one from Islamic Jihad and another from Fatah were killed in a gun battle at Jenin in the West Bank, the larger of the two Palestinian territories. Fatah remains dominant there.
Hamas, which won a parliamentary election 18 months ago but was shunned by Western powers for refusing to renounce violence and recognize Israel, was dismissed from government last week by Abbas after the Islamists routed Fatah forces in Gaza.
The result has been a schism that leaves Gaza, a 40-km (25-mile) strip of Mediterranean coast, isolated behind a dense Israeli military cordon and tightening economic blockade, while Abbas has secured promises that financial flows will be resumed to the separate, larger and Israeli-occupied West Bank inland.
U.S. President George W. Bush and Israeli Prime Minister Ehud Olmert pledged in Washington on Tuesday to bolster Abbas, while Israel sought to tighten the screws on Hamas in Gaza.