Two Israeli air strikes killed eight Palestinian militants Saturday in the latest signs that Israel has stepped up its retaliation for Palestinian rocket fire from Gaza since the Islamic militant group Hamas assumed power last week.

Six Palestinian militants were killed and five wounded when Israeli aircraft fired missiles after nightfall at a training camp in central Gaza, Palestinian officials said.

The Israeli military confirmed it carried out an attack against a Fatah camp that it said was used for weapons training and planning attacks against Israel.

Palestinians said the target was a camp used by the Abu Rish Brigades, an ad-hoc grouping of breakaways from several militant groups, including Fatah and Hamas.

Earlier Saturday, two members of the Al Aqsa Martyrs' Brigades, a violent offshoot of the Fatah Party, were killed and a third was seriously wounded in an Israeli missile strike on their car in Gaza. The militants had just fired a rocket toward Israel and returned to their car when they were hit, the Israeli military said.

Nabil Abu Rdeneh, a Palestinian Authority spokesman, said the air strikes were a "new escalation" and that the Palestinians would appeal to the U.N. Security Council to pass a resolution against the attacks.

In recent days, the military has also intensified artillery attacks on Gaza, for the first time firing at rocket launch sites even if they are in populated areas, rather than aiming only at open fields. Over a four-day period, two Palestinians have been killed and 25 wounded by direct artillery hits on houses, Palestinian officials said. Israeli security officials said troops have fired 750 artillery shells since Thursday.

The change in tactics comes at a time when Israel is revisiting its policy toward the new Hamas-led government. In an initial response to the Islamic militant group's election victory in January, Israel suspended monthly transfers of tax payments it collects on behalf of the Palestinian Authority and imposed travel bans on Hamas leaders.

Israel's Cabinet was to devise a more detailed policy in its weekly meeting Sunday.

Israel's designated prime minister, Ehud Olmert, said in an interview published on Newsweek's Web site Saturday that he would not try to negotiate a peace deal with moderate Palestinian President Mahmoud Abbas because he lost authority after Hamas' rise to power.

It marked the first time Olmert stated clearly that he will not negotiate with Abbas as long as Hamas does not recognize Israel, renounce violence and accept existing peace accords.

Hamas has said repeatedly it would not revise its positions, though some leaders in the group have hinted at a readiness to moderate.

If Hamas refuses to change, Olmert is expected to move ahead with his unilateral plan for the West Bank, including pulling out of large parts of the territory, but annexing large Jewish settlement blocs.

Asked how long he is prepared to wait before launching his West Bank plan, Olmert said: "If we reach the conclusion that the Palestinians are not prepared to meet the requirements that lead to negotiations, we will then move forward without a negotiating process. We are ready to change. We are not prepared to wait forever."

Olmert said peace talks would have to be conducted with the Palestinian Authority, now led by Hamas, and not with Abbas.

"Abu Mazen (Abbas) has deprived himself of all the practical authorities of government," he said.

Abbas meanwhile said in an interview to be published Sunday that Hamas has begun to realize after just a few days in power that it cannot govern without the world's recognition. But Hamas is still grappling with the international community's demands that it recognize Israel and renounce violence.

The European Union and the United States said Friday they are halting hundreds of millions of dollars in aid to the Palestinian Authority.

Palestinian Prime Minister Ismail Haniyeh, of Hamas, called the decisions "blackmail," and said Saturday his government would not change its positions.

On Friday, a missile strike killed five Hamas-linked militants and a 7-year-old boy in an attack on a militants' training camp in southern Gaza. Fourteen people were wounded.

Israeli military commentator Alon Ben-David said the army was following a policy of "intentional escalation," in part because of frustration over being unable to halt rocket fire from Gaza.