The Clinton administration yesterday ordered the federal government's export finance agency to delay approval of $500 million in credit guarantees to a Russian oil company following complaints by Western investors that they were being swindled out of their investments in Russia.

The proposed loans to the Tyumen Oil company--the largest U.S.-backed credits to a Russian company since the collapse of the ruble last year--have been the target of a massive lobbying effort by disgruntled Western investors in Russia and human rights organizations dismayed by the war in the rebellious republic of Chechnya, now under siege by Russian forces.

The decision to temporarily halt the loans came after several days of intense discussions within the White House and State Department over whether to invoke a seldom-used legal authority to override the decisions of the U.S. Export-Import Bank. The State Department announced that Secretary of State Madeleine K. Albright had advised the Ex-Im Bank that it was in the "national interest" not to go ahead with the loan "for the time being."

Administration officials made clear that the war in Chechnya played little role in their deliberations, and that their overriding concern was to protect the rights of Western investors in Russia. While the Clinton administration has criticized Moscow for its brutality in Chechnya, it has been less outspoken on the issue than its West European allies, several of whom have threatened the Kremlin with economic sanctions.

Three leading presidential contenders--Texas Gov. George W. Bush (R), Sen. John McCain (R-Ariz.) and former senator Bill Bradley (D-N.J.)---have called for a cutoff in Ex-Im Bank lending to Russia because of the Chechen war. Vice President Gore, who is heavily identified with U.S. policy toward Russia, has expressed concern about Tyumen's business practices, but has stopped short of demanding a halt to Ex-Im Bank lending.

Albright's intervention came just hours before the four-member board of the Ex-Im Bank was to give final approval to loan guarantees totaling nearly $500 million for upgrading Tyumen's oil operations in Russia. Bank Chairman James A. Harmon had resisted intense--but informal--administration pressure to delay the loans, arguing that Tyumen had met all the bank's financial criteria.

As the administration struggled to decide how to handle the controversy, there were signs that Tyumen may be on the verge of a settlement with its leading Western critics that will defuse their opposition to the loan. American business sources said they were expecting a deal to be announced in Moscow as early as Wednesday morning restoring the interests of major Western investors such as the oil giant BP Amoco and the financier George Soros in the highly profitable Chernogorneft field in western Siberia, which was acquired by Tyumen last month in a controversial bankruptcy auction.

The deal would bring Tyumen Oil into a partnership with Western investors who have accused it of a variety of corrupt or illegal practices. A civil lawsuit filed in New York last month by an investment group that includes the Soros Fund and Harvard University described Tyumen's moves to acquire Chernogorneft--at the expense of BP Amoco and Soros--as "one of the most brazen acts of corporate theft in recent memory."

Alan P. Larson, undersecretary of state for economic affairs, said the administration wanted to "work with Ex-Im to address the allegations" that have been made against Tyumen. He said that the allegations against Tyumen of trampling on the rights of foreign shareholders were "a particular concern given our policy of promoting the rule of law" in Russia.

While the administration has temporarily delayed approval of the credit guarantees for Tyumen, it has sought to protect its overall relationship with Russia, and insulate other financial dealings from the furor over Chechnya. World Bank officials said they planned to go ahead with a planned $100 million disbursement to the Russian government this week despite complaints from the human rights organization Helsinki Watch that the money could be used to help fund the Chechen campaign.

The International Monetary Fund held up a $640 million installment of a loan to Russia earlier this month in what officials said was a response to concerns by European governments about Chechnya.

Western business sources said the deal taking shape in Moscow over the carve-up of Chernogorneft would probably result in Tyumen's competitors dropping their allegations of unfair business practices, leaving the U.S. government with little to object to. Under the deal, BP Amoco would have three seats on the 11-member board of a restructured "Siberian Far Eastern Oil Co.," with management responsibility for the Chernogorneft field.

If the final details can be worked out, the deal will result in a partnership between some of Russian capitalism's most prominent tycoons and oligarchs, such as Mikhail Fridman and Oleg Potanin, who have been bitter foes in the past.

CAPTION: Secretary of State Madeleine K. Albright said loans were not in the "national interest."