The Israeli air force pounded targets in the northern Gaza Strip early on Wednesday, without causing casualties, following rocket fire on southern Israel, sources on both sides said.
Palestinian security sources confirmed the strike had hit a training camp in Beit Lahiya which was used by militants from the Ezzedine al-Qassam Brigades, the armed wing of the ruling Hamas movement.
"IAF aircraft targeted a terror tunnel in the northern Gaza Strip. Direct hits were identified," a statement from the Israeli military said.
"The targeting is in response to over 40 rockets that were fired at Israel this week, with seven of them fired in the past 24 hours."
Late on Tuesday, Israel police spokesman Micky Rosenfeld said five rockets had hit "close to the towns of Sderot and Netivot" which lie near the northern part of the Gaza border. There were no casualties or damage.
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Early on Wednesday, a small group of radical Salafists claimed the rocket fire in a statement sent to AFP, saying it was in response to recent air strikes on Gaza.
The group also said it was in response to clashes between Israeli police, rightwing Jewish activists and Muslim worshippers at Jerusalem's Al-Aqsa mosque compound, which is revered by Jews as the Temple Mount.
Earlier this week, the armed wings of Hamas and Islamic Jihad fired a barrage of projectiles at southern Israel a day after the air force raided the southern city of Rafah, targeting two men whom the military said were global jihad activists.
The two were critically wounded in the strike and one later died of his injuries. Another eight people were wounded, among them five children.
Monday's rocket fire by Hamas and Islamic Jihad militants marked a rare show of force given that the two group normally observe a de facto truce on rocket fire on Israel.
The last time Hamas militants fired on Israel was during a flareup in June when militant groups fired more than 150 rockets, wounding five people, and Israel hit back with air strikes that killed 15 Palestinians.