Israel's prime minister, Ariel Sharon, convened a special government committee on the matter, and the officials recommended for release a group of Palestinian prisoners whose cases have been reviewed by Israel's security service, Shin Bet. 

The Shin Bet list now has 520 names, up from about 350 that were approved by Mr. Sharon's cabinet on July 6, an Israeli official said. 

No date has been set for the releases. They could take place before Mr. Sharon's meeting on Tuesday with President Bush in Washington, or they might require further discussion in the full cabinet, Israeli officials said.

Mr. Sharon told the committee that "there has been significant Palestinian activity in preventing terror and incitement," according to a statement released by his office.

However, Mr. Sharon said the Palestinian leadership had not moved to "dismantle the terrorist organizations or their infrastructure."

The release of Palestinian prisoners is not part of the Middle East peace initiative, called the road map. But the Palestinian prime minister, Mahmoud Abbas, has made it a top priority and is expected to raise the issue at his meeting with President Bush on Friday.

Speaking about the meeting in general terms, the Palestinian information minister, Nabil Amr, said that "if there is no progress in this important visit to Washington, we can be sure that Prime Minister Mahmoud Abbas will face a tough situation among the Palestinian people and the Legislative Council."

Hisham Abdel Raziq, the Palestinian minister in charge of prisoner affairs, met Avi Dichter, the chief of Shin Bet, on Tuesday night, but they failed to achieve any breakthroughs.

In Gaza City, several hundred Palestinians gather daily at a tent in a park in the city center to call for the release of prisoners.

The Palestinians are seeking the release of all prisoners held by Israel, a figure believed to be close to 6,000. The vast majority have been detained during the current fighting, which began in September 2000.

Israel has freed about 300 Palestinians in recent weeks, and says it will continue to consider additional releases if the Palestinians take action against militants. But Palestinians say progress on the prisoner issue is essential to moving forward with the overall peace effort.

Israel has said it will not release any Palestinians with "blood on their hands." The government also has said it will not free any members of Hamas or Islamic Jihad, the two groups that have carried out most of the suicide bombing attacks. However, some Israeli government officials have said that members of those groups should also be considered.

In Washington today, the Israeli foreign minister, Silvan Shalom, said the number released so far constituted a significant gesture to Mr. Abbas, and outstripped previous releases. "It's important to understand, it's a huge number of prisoners," Mr. Shalom said. He dismissed the Palestinian contention that Israel should free more.

The foreign minister, who is preparing the terrain for the visit by Mr. Sharon next week, said Israel will follow through with a series of other gestures aimed at improving the quality of life of Palestinians.

The good-will steps include issuing them more work permits, allowing workers to stay overnight in Israel, and expanding fishing rights off the beach in Gaza from 8 to as much as 12 miles.

In addition, Mr. Shalom said, the Israeli government will continue to dismantle illegal outposts in the occupied territories. So far, Israel has removed 20 of them. But some of them are little more than trailers, he conceded, which are readily moved to other illegal sites.

Mr. Shalom said that weapons continued to be smuggled into Israel across the Egyptian border. He dismissed claims that Mr. Abbas and the Palestinian Authority were powerless to control extremists.

In areas where Israel has withdrawn — Gaza and Bethlehem — he said, there are 20,000 armed employees of the Palestinian Authority capable of cracking down on what he said were "only a few hundred activists."

Richard Boucher, the State Department spokesman, said the administration would continue to press both Israel and the Palestinians to honor their commitments and advance the peace process.

"Both parties continue to have obligations," he said. "There are more things that people need to do. We don't want to fall backwards, we want to keep moving forward."