Gaza fighters on Wednesday continued their retaliation for the killing of a member of a Palestinian resistance group on Monday, firing rockets into the Zionist state.

Two people received shrapnel wounds and three cars were damaged as one of 15 rockets fired at southern Israel struck outside a supermarket in the city of Sderot, the army said.

Israeli forces immediately launched an air strike in northern Gaza, hitting a rocket launcher that was about to fire, a military spokeswoman said.

Islamic Jihad said its armed wing, the Al-Quds Brigades, fired rockets in retaliation for Monday's killing by Israeli forces of one of its members in the Occupied West Bank.

The movement had claimed similar attacks on Monday, which were followed by two Israeli air strikes in Gaza.

The attacks came just ahead of the conclusion of the six-month cease-fire that went into effect on June 19.

Hamas, the Islamist movement that rules Gaza, has spoken out against extending the truce, but it indicated it has yet to take a final decision.

"Friday, December 19 is the last day of the calm," said Ismail Radwan, a Hamas leader in Gaza, adding that the movement "will respond to any aggression by the occupying forces against our people."

The Egyptian-mediated deal that went into effect in June had brought months of calm in and around the Gaza Strip. But on November 4, Israel shattered the deal by invading the coastal territory in an attack in which seven Hamas members were killed. The invasion prompted Palestinian fighters to resume rocket attacks against Israel.

Despite breaking the deal, Israeli officials have said they want to continue the truce but warned they would not hesitate to use military force should Gaza militants fail to halt their rocket and mortar attacks.

Since the November 4 invasion and the attacks it prompted, Israel has completely sealed off Gaza except for a few humanitarian aid deliveries.

The impoverished territory, where roughly half of its 1.5 million inhabitants rely on handouts from the international community for survival, has been under a crushing Israeli siege since Hamas won legislative elections in 2006.Israel controls all access in and out of Gaza - with the exception of one land crossing with Egypt - including the territory's sea and airspace.

Following the 2007 ouster of Fatah from the territory in what many have described as a pre-empting of an impending US-backed offensive by Fatah to oust the Islamists from Gaza, Israel further tightened its grip.

Humanitarian agencies and human-rights groups have urged Israel to lift the blockade, saying the population of Gaza should not be punished for the actions of the resistance.

In an opinion sent to Attorney General Menahem Mazuz, Israel's legal watchdog group Gisha warned that the restrictions on the passage of people and goods amounted to "a closure imposed for the illegal purpose of collective punishment against innocent civilians."

Collective punishment of a civilian population is illegal under international law and is defined by the Fourth Geneva Convention as a war crime.

Last week, Richard Falk, a UN human-rights observer to Palestine who has since been bared from undertaking his mandate by Israel, described the policies of the Zionist state a "crime against humanity."

Several Israeli ministers, though, have called for a tougher line against retaliations from Gaza fighters, and Foreign Minister Tzipi Livni, who hopes to become premier after the February 10 elections, has said Israel "cannot allow Gaza to remain in the hands of Hamas."

Palestinian President Mahmoud Abbas, who headed to Washington Wednesday, plans to discuss the situation in Gaza during his talks on Friday with US President George W. Bush.

Abbas "will warn against an Israeli offensive in Gaza and will call for the lifting of the Israeli blockade," said Palestinian negotiator Saeb Erakat.

Abbas also called for a continuation of the truce, although he has had no influence in Gaza since his forces were driven out when Hamas seized power.

The situation in Gaza, and the divisions between Hamas and Fatah have further complicated Israeli-Palestinian peace talks that have produced no tangible results since they were revived under US auspices in November 2007.

The peace process has also been marred by Israel's shattering of the Gaza truce and continued Israeli settlement construction - despite pledging to halt the practice, which is illegal under international law.