By Raymond Bonner

Washington -- As part of the campaign against President Slobodan Milosevic of Yugoslavia, the Clinton administration and NATO have tried to cut off his oil supply and his bank accounts.

It is a campaign that has not gone well, American and NATO officials say. Barges are filled with oil in Ukrainian ports and cross the Black Sea to chug up the Danube River through Bulgaria and Romania. To pay for it, Milosevic is using money he secreted in banks in Cyprus during the earlier period of sanctions against Yugoslavia, the officials said. The administration and European governments have appealed to Ukraine to shut down the trade and they have asked Cyprus to freeze Milosevic's bank accounts, American and NATO officials say, but to no avail.

During his visit to Washington last week, Gen. Wesley Clark, NATO's commander, raised alarms about the oil shipments traveling up the Danube and said that action needed to be taken to stop them. He said this route was increasingly being used because NATO had been somewhat successful in choking off the supply coming into Montenegro.

American officials say that they do not have a good fix on the volume of oil Milosevic is getting through this route -- he is still getting some from ships unloading at Montenegrin ports -- but they say that it is Russian oil. The deals are being arranged by middlemen who are making a tremendous profit because of the risks involved, the officials say. Asked how much oil Milosevic was getting, one administration official said, "All he needs." Another official said that was an exaggeration, but he conceded that the Serbian leader was getting enough oil to keep his military machine going. A third official replied, simply, "Too much."

The Clinton administration and NATO have tried to deal with the matter quietly, fearing that making it a public issue could backfire.

When an oil embargo was last in effect against Yugoslavia, from 1992 until the signing of the Dayton peace accords in 1995, Bulgaria and Romania were major conduits for oil in violation of the sanctions. (Greek and Italian oil companies were major suppliers, with most of their oil moving through Albania, a route that has now been largely shut down.)

But Washington and European capitals expect to have more success now. The governments in Bulgaria and Romania have become more stable and have better-trained law enforcement agencies; above all, they have moved from their Communist pasts, expressing a strong desire to get into NATO and the European Union. Still, Bulgaria and Romania have not been as cooperative as the administration would like.

The governments argue that they cannot interfere with traffic on the Danube because it is an international waterway covered by the Danube Convention of 1948, which calls for free movement of ships. But American officials dismiss those assertions, noting that the convention was signed by the Danube riparian states when they were part of the Soviet bloc; West Germany was the one Danube state that did not sign.

Above all, American and NATO officials say, the major problem is Ukraine, which is the source of the oil transportation. Last week during meetings in Brussels, Belgium, Boris Tarasyuk, Ukraine's foreign minister, was cordially but firmly told that his country must stop the barges from loading up with oil in the Ukrainian ports, a NATO official said.

Tarasyuk countered with complaints about the economic damage Ukraine was suffering because of the war against Yugoslavia. He said that it had cost his country $220 million in lost trade, that Ukrainian ports alone had lost $12 million, and that a Danube shipping company in Ukraine was losing $313,000 a day. Who was going to compensate Ukraine for that, he demanded of the NATO diplomats.

The Clinton administration and NATO are not confident that they will prevail upon the Ukrainian government. Nearly 90 percent of the Ukrainian population is against the NATO bombing, according to recent polls there, an American official said. It is for this same reason that the administration does not feel that it can make a public issue out of Ukraine's lack of cooperation.

In Cyprus, too, the Clinton administration is worried about upsetting the government and so has not said anything publicly, but it is not happy that the Cypriots have refused to close the bank accounts belonging to Milosevic and to the Yugoslav government. With its secretive banking laws, Cyprus has become a major money-laundering center, especially for Russian organized criminal operations, American and European law-enforcement officials say. European law enforcement officials say that many of the continent's cigarette-smuggling operations use Cyprus, including an operation in which one of Milosevic's sons is involved.

American officials say they do not know how much Milosevic has in these accounts, in part because finding his assets had never been a priority of the CIA, several officials said.

But however much is in them, the Cypriots argue that there is no basis for seizing the bank accounts because there are no United Nations sanctions against Yugoslavia. Most of the sanctions against Yugoslavia that were imposed in 1992 were lifted after the Dayton peace accords in 1995. But back when the sanctions were in effect, Cyprus did not cooperate either. "They always found loopholes," an American official said.