Israeli airstrikes have killed at least nine Palestinian fighters making it the highest single death toll since a 2012 eight-day cross-border war.
Two of the men from the Al Hussinin brigade, a military group belonging to Fatah, were targeted by drone strikes east of the Bureij refugee camp in central Gaza on Sunday, witnesses said.
Seven fighters from the Al Qassam brigades, the armed wing of Hamas, were killed when an air strike hit a tunnel at Rafah, in the south of Gaza.
In a statement, Israel's army said it "has succeeded in stopping another attack against Israel by targeting terrorists who are implicated in launching rockets from central Gaza". "The target was hit," said the statement.
Earlier, the Israeli army carried out a drone strike against an armed group in Gaza, but the targets managed to escape, witnesses said.
Fighters in Gaza have fired at least 25 rockets and mortar shells over the border since Sunday morning, after a night of 10 air strikes.
The strikes come after the abduction and killing of 16-year-old Mohammad Abu Khdeir on July 2, a suspected act of revenge for the killing of three Israeli youths, whose disappearances and deaths have heightened tension in the region.
On Thursday Abu Ubaida, spokesman for Hamas' armed wing, Al-Qassam Brigades accused Israel breaching a cease-fire brokered after a 2012 eight-day cross-border war and said the group would respond according to developments on the ground.
On Friday, Israeli police clashed with hundreds of Palestinian protesters in Jerusalem at the funeral of Abu Khdeir who was burned alive, according to initial post-mortem findings reported by local media citing the Palestinian attorney general.
On Sunday, Israeli police arrested six people in connection who Palestinians say was killed in revenge for the murder of three teenage settlers last month.
The Israeli military has launched scores of airstrikes on the Gaza Strip in the past weeks that have killed two and injured several, and armed groups in the territory have shot dozens of rockets into southern Israel.
Al Jazeera and wire services
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