Hamas hardened its stance on Saturday after a new barrage of Israeli airstrikes killed five militants, saying it would not consider a truce and calling for more attacks on Israel.

The Islamic militant group also warned Israel that if it continued its 10-day air assault, it would threaten the release of Cpl. Gilad Shalit, the Israeli soldier nabbed last June by Hamas-linked militants. Shalit has not been heard from or seen since his capture.

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Abbas, a moderate from the rival Fatah faction, has tried in recent days to revive a cease-fire with Israel. Under his plan, Gaza militants would halt rocket fire for a month to allow for negotiations on a more comprehensive truce that would include the West Bank.

After a meeting late Friday, the militant groups initially asked for 48 hours to consider the proposal and respond.

But after the rash of new air attacks Saturday, including five in less than an hour, Hamas called on its fighters to "direct painful strikes at the Zionist enemy." Hamas "will not offer a free truce to the Zionist occupation," the group said.

"If there is an end to the attacks, we can talk about a truce," said Abu Obeida, a spokesman for the Hamas military wing.

He said Shalit's freedom was in danger, but not his life.

"The enemy knows that getting Shalit back is in our hands," he said. "It would be a dream" that Hamas would release him while attacks continued, he added.

Israel has launched dozens of targeted missile strikes over the past 10 days that have killed 48 Palestinians and damaged many Hamas installations in an attempt to stop Hamas rocket fire from Gaza at Israeli border towns.

Israel said some 225 rockets have landed in Israeli towns since May 15, killing one woman and sending thousands of frightened Israeli residents fleeing. Two rockets landed in Israel on Saturday, including a direct hit on a home in Sderot. No one was injured.

In all, Israeli aircraft launched 12 missile strikes Saturday. Before dawn, they struck near the house of Prime Minister Ismail Haniyeh of Hamas in a Gaza refugee camp, while troops in the West Bank arrested a Hamas Cabinet minister.

There was also a rare incident of violence in East Jerusalem late Saturday when two Palestinian gunmen opened fire at an Israeli security patrol near the separation barrier Israel is erecting along Jerusalem's municipal boundary.

Israeli border police at the scene fired at the attackers, killing both of them. Israeli emergency services said two Israelis were injured and evacuated to hospital. An offshoot of the violent Al Aqsa Martyrs' Brigade, which is affiliated with Fatah, claimed responsibility for the shooting, according to the Palestinian news Web site Maan.

One of the Israeli airstrikes hit a key Hamas base in Gaza City, killing five Hamas members and wounding four. The compound was used as a training center and base for Hamas' militia, the Executive Force. Two rooms in the camp were destroyed and rescue workers searched the rubble. A nearby charity was badly damaged from the strike. Hamas gunmen shot in the air to disperse a crowd of onlookers.

Earlier Saturday, two missiles hit close to Haniyeh's house in the Shati refugee camp on the outskirts of Gaza City. One landed around 100 yards away and the other 300 yards away, hitting trailers used by Haniyeh's bodyguards.

"This is a critical stage," said Haniyeh in a statement hours after the strike. "The aggression will not achieve its goal, but will lead to more disturbance and will have serious consequences."

The army confirmed the Shati strikes but said Haniyeh was not a target.

In a rare appearance, Abu Obeida al-Jarrah, the Chief Commander of the Executive Force, a pro-Hamas security apparatus, said Israel's targeting of its bases was "a declaration of war" in coordination with its "agents" in Gaza Strip. Hamas has accused members of its rival Fatah of serving Israel's interests.

Michael C. Williams, the U.N.'s new envoy to the Middle East, met Saturday with Abbas in Gaza.

"I'm very troubled by the level of violence here," he said. "I think the U.N., the international community in general, have been very concerned about the level of intra-Palestinian violence, but also by the Israeli attacks which I know have caused civilian deaths, considerable numbers."

In the West Bank, Israeli troops arrested Cabinet minister Wasfi Kabaha. The arrest came two days after a sweep in which more than 30 Hamas politicians, legislators and local council members were arrested, including the education minister.

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