WASHINGTON, July 27 — The Bush administration is preparing to ask Congress to approve an arms sale package for Saudi Arabia and its neighbors that is expected to eventually total $20 billion at a time when some United States officials contend that the Saudis are playing a counterproductive role in Iraq.

The proposed package of advanced weaponry for Saudi Arabia, which includes advanced satellite-guided bombs, upgrades to its fighters and new naval vessels, has made Israel and some of its supporters in Congress nervous. Senior officials who described the package on Friday said they believed that the administration had resolved those concerns, in part by promising Israel $30.4 billion in military aid over the next decade, a significant increase over what Israel has received in the past 10 years.

But administration officials remained concerned that the size of the package and the advanced weaponry it contains, as well as broader concerns about Saudi Arabia’s role in Iraq, could prompt Saudi critics in Congress to oppose the package when Congress is formally notified about the deal this fall.

In talks about the package, the administration has not sought specific assurances from Saudi Arabia that it would be more supportive of the American effort in Iraq as a condition of receiving the arms package, the officials said.

The officials said the plan to bolster the militaries of Persian Gulf countries is part of an American strategy to contain the growing power of Iran in the region and to demonstrate that, no matter what happens in Iraq, Washington remains committed to its longtime Arab allies. Officials from the State Department and the Pentagon agreed to outline the terms of the deal after some details emerged from closed briefings this week on Capitol Hill.

The officials said Secretary of State Condoleezza Rice and Defense Secretary Robert M. Gates, who are to make a joint visit to Saudi Arabia next week, still intended to use the trip to press the Saudis to do more to help Iraq’s Shiite-dominated government.

“The role of the Sunni Arab neighbors is to send a positive, affirmative message to moderates in Iraq in government that the neighbors are with you,” a senior State Department official told reporters in a conference call on Friday. More specifically, the official said, the United States wants the gulf states to make clear to Sunnis engaged in violence in Iraq that such actions are “killing your future.”

In addition to promising an increase in American military aid to Israel, the Pentagon is seeking to ease Israel’s concerns over the proposed weapons sales to Saudi Arabia by asking the Saudis to accept restrictions on the range, size and location of the satellite-guided bombs, including a commitment not to store the weapons at air bases close to Israeli territory, the officials said.

The package and the possible steps to allay Israel’s concerns were described to Congress this week, in an effort by the administration to test the reaction on Capitol Hill before entering into final negotiations on the package with Saudi officials. The Saudis had requested that Congress be told about the planned sale, the officials said, in an effort to avoid the kind of bruising fight on Capitol Hill that occurred in the 1980s over proposed arms sales to the kingdom.

In his visit with King Abdullah and other Saudi officials next week, Mr. Gates plans to describe “what the administration is willing to go forward with” in the arms package and “what we would recommend to the Hill and others,” according to a senior Pentagon official, who conducted a background briefing on the upcoming trip with reporters on Friday.

The official added that Mr. Gates would also reassure the Saudis that “regardless of what happens in the near term in Iraq that our commitment in the region remains firm, remains steadfast and that, in fact, we are looking to enhance and develop it.”

The $20 billion price tag on the package is more than double what officials originally estimated when details became public this spring. Even the higher figure is a rough estimate that could fluctuate depending on the final package, which would be carried out over a number of years, officials said.

Worried about the impression that the United States was starting an arms race in the region, State and Defense Department officials stressed that the arms deal was being proposed largely in response to improvements in Iran’s military capabilities and to counter the threat posed by its nuclear program, which the Bush administration contends is aimed at building nuclear weapons.

Along with Saudi Arabia, Bahrain, Kuwait, Oman, Qatar and the United Arab Emirates are likely to receive equipment and weaponry from the arms sales under consideration, officials said. In general, the United States is interested in upgrading the countries’ air and missile defense systems, improving their navies and making modest improvements in their air forces, administration officials said, though not all the packages would be the same.

Ms. Rice is expected to announce Monday that the administration will open formal discussions with each country about the proposed packages, in hopes of reaching agreements by the fall.

Along with the announcement of formal talks with Persian Gulf allies on the arms package, Ms. Rice is planning to outline the new agreement to provide military aid to Israel, as well as a similar accord with Egypt.

The $30.4 billion being promised to Israel is $9.1 billion more than Israel has received over the past decade, an increase of nearly 43 percent.

A senior administration official said the sizable increase was a result of Israel’s need to replace equipment expended in its war against Hezbollah in Lebanon last summer, as well as to maintain its advantage in advanced weaponry as other countries in the region modernize their forces.

In defending the proposed sale to Saudi Arabia and other gulf states, the officials noted that the Saudis and several of the other countries were in talks with suppliers other than the United States. If the packages offered to them by the United States are blocked or come with too many conditions, the officials said, the Persian Gulf countries could turn elsewhere for similar equipment, reducing American influence in the region.

The United States has made few, if any, sales of satellite-guided munitions to Arab countries in the past, though Israel has received them since the mid-1990s as part of a United States policy of ensuring that Israel has a military edge over its regional rivals.

Israeli officials have made specific requests aimed at eliminating concerns that satellite-guided bombs sold to the Saudis could be used against its territory, administration officials said.

Their major concern is not a full-scale Saudi attack, but the possibility that a rogue pilot armed with one of the bombs could attack on his own or that the Saudi government could one day be overthrown and the weapons could fall into the hands of a more radical regime, officials said.