RAMALLAH/GAZA, 29 May 2007 — Hamas defied a cease-fire call by Palestinian President Mahmoud Abbas and Israeli threats to escalate military strikes in the Gaza Strip by firing rockets into Israel.

In the first internal Palestinian violence since a May 19 cease-fire, fighting between Hamas gunmen and members of a security force loyal to Abbas’ Fatah faction erupted in the territory. There were no reports of casualties.

Earlier, a special Israeli forces unit arrested yesterday Khaled Al-Shaweesh, one of the high-ranking of the Fatah-affiliated Al-Aqsa Martyrs’ Brigades in Ramallah, Palestinian sources said. Israeli security sources confirmed the arrest of Shaweesh in Ramallah in a joint Israeli Army and Shin Bet operation in the city.

Israeli officials said that Al-Shaweesh was behind dozens of attacks including bombing attacks in Jerusalem as well as shooting attacks on roads in the Ramallah area.

In Jericho, the Israeli forces yesterday nabbed the leader of Al Aqsa Martyrs Brigades Omar Abu Daya, Palestinian sources said. At least seven rockets struck the town of Sderot in southern Israel but no one was hurt, the military said. Previous salvoes during an almost two-week-old surge of cross-border fighting have killed two Israelis — one a motorist hit on Sunday.

Israel has struck back with an aerial bombing campaign that has killed more than 40 Palestinians in Gaza, most of them militants. Yet the failure to end the rocket barrages has prompted the Israeli government to speak of tougher action.

“I think the measures are effective but not enough, and we have a large battery of some more steps that I hope we will be able to take,” Internal Security Minister Avi Dichter told Reuters during a visit to Sderot. He did not elaborate.

Israeli Prime Minister Ehud Olmert said on Sunday that Hamas would be fought “without limitation.” Meanwhile, citing “security concerns” stemming from Olmert’s comments, Palestinian Prime Minister Ismail Haniyeh of Hamas stayed away from a weekly Cabinet meeting at his Gaza office yesterday, a government official said.

Abbas, who agreed a now-defunct Gaza truce with Olmert in November, has been trying to coax Hamas’ armed wing and other militants into holding their fire again.

In new factional violence, Hamas security men exchanged fire with members of one of Abbas’ forces in Gaza, residents said. Fatah said Hamas men attacked a vehicle carrying a Force 17 officer. Hamas was not immediately available for comment.

— With input from agencies