Israeli aircraft carried out air strikes against Hamas militants in the Gaza Strip and Israeli tanks moved to the Gaza border on Thursday. VOA's Jim Teeple reports a planned meeting of Palestinian leaders in Gaza was called off as violence that has claimed more than 50 Palestinian lives since Sunday continued.

Smoke rises from an explosion following an Israeli airstrike on a building used by the militant group Hamas in Gaza City,  17 May 2007

After several days of rocket attacks against southern Israel -- Israeli forces struck back with force on Thursday -- destroying a command center used by Hamas militants in Gaza City.

Hamas has claimed responsibility for the rockets against southern Israel over the past few days which have forced the evacuation of the Israeli city of Sderot, which is near the Gaza border.

Prime Minister Ehud Olmert has warned of a severe response to the attacks. At the same time his spokesperson, Miri Eisen, says Israel does not want to send its military back into the Gaza Strip.

"Right now the state of Israel in this very complex situation very clearly states we will defend our citizens, we will not be dragged by the Hamas back into the mud of Gaza," she said. "But we also will clearly fight against the terror that they are exporting and not allow them to drag us into their own domestic violence."

A truce between Israel and Palestinian militant groups agreed to last November has largely held. Senior Israeli officials say while they will carry out limited military operations against targets in Gaza, they have no plans for a large scale military invasion at this time.

The Israeli strike came as Palestinian President Mahmoud Abbas cancelled a trip to Gaza where he was to meet with Prime Minister Ismail Haniyeh. Mr. Abbas heads Fatah, and Ismail Haniyeh is a senior leader of Hamas.

Gunmen from the two groups have been fighting each other over the past week. The violence flared after Mr. Abbas deployed several thousand Palestinian police in Gaza without coordinating with Hamas officials.

Saeb Erekat, a close aide to Mr. Abbas, says the Palestinian president still plans to travel to Gaza -- to try and get security forces from both groups to operate under a joint command.

"I think the president wants to go with a government in terms of implementing the security plan whereby they have to restore the rule of law, the one authority -- the one gun," he said. "That is what is needed."

Erekat says for now Mr. Abbas has no plans to declare a state of emergency -- essentially taking control of the Palestinian government himself -- in a bid to end the factional fighting. The violence over the past week has raised fears that the two-month old Palestinian unity government could collapse.