GAZA CITY, Gaza Strip - Israeli aircraft attacked suspected weapons factories throughout the Gaza Strip today, pressing an offensive against Palestinian militants despite a pledge by a top Hamas leader to halt rocket fire.

The airstrikes knocked out power to eastern Gaza City and damaged several buildings, but no injuries were reported. Israeli security officials said they would wait to see whether Palestinian attacks would in fact halt before calling off the military assault launched over the weekend.

The fighting came ahead of a key vote today in Prime Minister Ariel Sharon's Likud Party on when to hold a primary election. It is widely seen as a test of Sharon's leadership.

Sharon, under fire from party hard-liners over recent withdrawal from Gaza two weeks ago, walked out of a stormy Likud meeting Sunday night without delivering his prepared speech. A problem with the sound system prevented him from speaking. Some Likud officials said the system was sabotaged by Sharon opponents.

Israel launched the weekend offensive following a rocket barrage from Gaza into nearby Israeli towns.

It has carried out a series of airstrikes, killing four militants and destroying several weapons facilities, and has arrested more than 200 Palestinians. The fighting has destroyed any goodwill from the Gaza pullout and increased already intense pressure on Palestinian leader Mahmoud Abbas to confront militants.

Abbas has said his forces are not strong enough to take on militants, and that he fears civil war among the many armed groups in Gaza.

The attacks today struck targets around Gaza City as well as the southern towns of Rafah and Khan Younis. The army said its targets included an access road leading to a rocket-launching site in northern Gaza, and weapons-manufacturing factories and storage facilities belonging to various militant groups.

The Gaza City airstrike destroyed a metal workshop the army said was used by Hamas to make weapons. Factory owner Ali Shaaban said it was the fourth time the workshop had been targeted. Shaaban said he produced engine parts for vehicles and generators, not weapons.

Israel pressed ahead with its air campaign despite a call by Hamas leader Mahmoud Zahar to end the group's rocket attacks. Zahar spoke at a news conference late Sunday, hours after a pinpoint Israeli airstrike killed a top commander in the Islamic Jihad militant group.

Zahar said his Islamic militant group remained committed to a seven-month-old cease-fire and he wanted to prevent further Israeli attacks.

The recent violence erupted following an explosion at a Hamas parade last Friday which killed 20 people in a Gaza refugee camp.

Hamas accused Israel of setting off the explosion. But Palestinian Authority officials said investigators determined the blast was caused by the mishandling of explosives. Israel, which routinely claims responsibility for attacks on militants, denied involvement.

Following the explosion, Hamas militants fired nearly 40 rockets into southern Israel, injuring six people and touching off the Israeli offensive. Officials said the offensive would continue until the rocket fire ends.