WASHINGTON (Reuters) - The Bush administration is preparing to tell Congress next month it plans to sell Saudi Arabia and its Persian Gulf Arab neighbors billions of dollars in advanced arms as a counterweight to Iran, Syria and what it calls militant groups.

""We expect to make the formal notification of the initial sales soon,"" before Congress recesses next month, a State Department official familiar with the matter said on Thursday.
A so-called pre-notification clock started on Tuesday with word to House of Representatives Speaker Nancy Pelosi, said Rep. Anthony Weiner, a New York Democrat pressing to block the most controversial proposed sale to Saudi Arabia.
At issue is a Boeing Co kit that turns unguided bombs into precision munitions -- a sale frowned on by Israel's backers in the U.S. Congress.
State Department officials have been consulting lawmakers in a drive to head off a potential drawn-out clash over these so-called Joint Direct Attack Munitions, or JDAMs.
The coming sales may include Patriot anti-missile battery upgrades for several countries, plus a new class of shore- patrolling warships for Saudi Arabia's eastern fleet, according to retired Air Force Lt. Gen. Jeffrey Kohler, who held talks on the matter before stepping down in August as the Pentagon's top arms-sale official.
The warship piece ""of the so-called package could run as high as $11 to $13 billion and take well over a decade before delivery of the last ship"" of up to 12 vessels, he said in a telephone interview.
U.S. suppliers likely to benefit from the new round of Gulf arms deals include Lockheed Martin Corp, Northrop Grumman Corp, General Dynamics Corp, Boeing and Raytheon Co.
Saudi Arabia is expected to be the biggest buyer. The others are fellow members of the Gulf Cooperation Council -- the United Arab Emirates, Kuwait, Qatar, Bahrain and Oman.
The deals could be worth a combined total of $20 billion over the years, Pentagon officials have told Congress, which has 30 days to vote to block a proposed sale from the formal notification date, but rarely does so.
The pre-notification clock that started on Tuesday lasts 20 days, meaning the formal process could start as soon as Dec. 4 or so -- leaving Congress little time to debate the issues before it recesses for the year.
The State Department and the Defense Department jointly laid out the rationale for the build-up at the end of July. Secretary of State Condoleezza Rice said the package would help ""bolster forces of moderation and support a broader strategy to counter the negative influences of al Qaeda, Hezbollah, Syria and Iran.""
Rep. Mark Kirk, an Illinois Republican, said some 150 Democratic and Republican members of Congress out of 535 had signed a letter he wrote voicing concern about JDAMs for Saudi Arabia, which remains in a formal state of war with Israel.
""The administration would be wise to listen to the voices of several prominent committee chairs, as well as ranking Republicans,"" Kirk said in a telephone interview on Thursday.
Israel and the Bush administration have agreed to disagree on the wisdom of selling JDAMs to Saudi Arabia, said Peter Rodman, who worked on the issue before retiring as an assistant secretary of defense earlier this year.
""But they're not going to fight against the administration"" over the JDAMs, Rodman, now at the private Brookings Institution, said in a telephone interview.
""What the Israelis are worried about is some Islamist Saudi pilot might peel off and try to fire a smart weapon at a key Israeli target,"" said Kenneth Katzman, a Middle East expert at the nonpartisan Congressional Research Service.
""They're also worried about a potential change of government in Saudi Arabia to a hard-line Islamist regime that might deliberately and purposely try to use that weapon against Israel.""
In separate but related deals, the Bush administration pledged earlier this year to boost U.S. military aid to Israel by 25 percent, to $30 billion, over 10 years, much of which is spent on U.S.-built arms. Over the same period, Egypt, the first Arab country to sign a peace treaty with Israel, will get $13 billion in U.S. military aid.