The American administration has promised Israel that the United States will not recognize any Palestinian government in which Hamas participates, government sources in Jerusalem have said.

The sources said that American envoys who visited here about 10 days ago told Israeli officials that recognizing such a government would violate American law.

Israel has also received similar messages from Javier Solana, the European Union's top foreign policy official, and Spanish Foreign Minister Miguel Moratinos, who visited Israel last week, the sources said.

Polls have shown that Hamas could win a third or more of the vote in the Wednesday elections for the Palestinian parliament, a showing that could prompt an offer from the ruling Fatah party to share power in a coalition government.

On Sunday, Palestinian Authority Chairman Mahmoud Abbas defended his decision to allow Hamas to run in the election, saying he hopes Hamas would tame its positions once it formally joins the political system.

Acting Prime Minister Ehud Olmert held a special meeting Sunday to discuss the PA elections. It was attended by Foreign Minister Tzipi Livni, Defense Minister Shaul Mofaz, Public Security Minister Gideon Ezra, Minister Tzachi Hanegbi and senior officials from the police, the Israel Defense Forces, the Shin Bet security service, the National Security Council and the Defense Ministry.

Olmert asked the participants not to offer concrete suggestions for action, lest the proposals leak and Israel be accused of trying to interfere in the elections. He also took the unusual step of declaring the entire discussion classified, even though it dealt with a civilian diplomatic issue - the Palestinian elections - rather than sensitive security matters.

At the meeting, several officials presented different possible scenarios for the outcome of the elections and their potential ramifications.

The defense establishment's prediction is that Fatah will win by a small margin. However, Israel is also preparing for the possibility that Hamas will participate in a Fatah-led government or even win the elections itself. But whatever happens, Israel will wait for both the official results and the formation of the new government before deciding on its next steps.

During the meeting, an argument erupted when National Security Council Chairman Giora Eiland disputed some of the assessments presented by Dov Weissglas, a senior adviser to the prime minister, and certain senior defense officials. As a result, Olmert decided that both sides should continue to produce independent assessments.

The main work will be done by the team headed by Weissglas, which includes the chief of staff, the head of the Shin Bet, the Foreign Ministry's director general and the prime minister's military secretary. This team will follow developments in the PA both during and after the elections and issue recommendations to the government. Their proposals will first be presented to Mofaz, and then, if he approves them, to a special ministerial committee headed by Olmert.

At the same time, however, Eiland and the NSC will independently draft their own recommendations for different post-election scenarios.

Olmert will present his own diplomatic program in a speech to the Herzliya Conference on Wednesday. The speech, which will call for resuming final-status negotiations after the PA dismantles the terrorist organizations, will deal extensively with the PA elections.