In a last-ditch effort to win Moscow's backing for the return of U.N. disarmament experts to Iraq, the United States has made concessions that could hasten the suspension of economic sanctions and might reopen Baghdad to limited air traffic, diplomats said today.

The United States and Britain are pushing for a vote as early as Monday on a U.N. Security Council resolution that would offer to ease the 9-year-old embargo on Iraq if Saddam Hussein's government allows U.N. weapons inspectors to return to the country and fully cooperates with them for some period of time.

To avert a Russian veto, diplomats said, the United States agreed to consider shortening that test period. U.S. negotiators previously insisted on a minimum of 180 days of Iraqi cooperation, while Russia called for 60 days. While the two sides have not yet reached agreement, the United States has indicated a willingness to compromise, diplomats said.

The United States also agreed to soften its opposition to the resumption of commercial flights to and from Baghdad. The latest draft of the resolution would allow flights for religious pilgrimages; it also holds out the possibility of lifting prohibitions on the "delivery" of various goods.

French diplomats interpret "delivery" to include transport by air, road and sea, although they acknowledge that the term is deliberately ambiguous, leaving the difficult question to be decided in the future.

A senior Clinton administration official said today the United States would not rule out a case-by-case exemption of flights carrying commercial goods, but he cautioned that the United States was not prepared to allow Iraq to resume business as usual. "We are willing to look at practical arrangements," he said. "But if you are asking about a major change on civil aviation, the answer is a flat no. We would definitely not agree."

The United States has refused to budge, however, on its position that Iraq must demonstrate "full cooperation" with arms inspectors before suspensions can be eased, according to U.S. officials. And the United States has insisted that tight controls be maintained on the use of any Iraqi oil revenue.

"The Americans have given a serious, substantive response to Russia," said an official close to the talks. "But there are limits to how much Russia can be accommodated."

Russia's U.N. ambassador, Sergei Lavrov, so far has refused to say whether his government will block the resolution, introduced by Britain, to establish a new U.N. arms control agency and send inspectors back into Iraq. The previous U.N. Special Commission, or UNSCOM, was evacuated on the eve of a U.S.-British airstrike one year ago.

But Lavrov indicated today that the American concessions did not go far enough. "The problem with this resolution is, it is very ambiguous, the trigger is ambiguous, and the scope of suspension is ambiguous," he said.

The 15-member Security Council, meanwhile, voted today to permit Iraq to sell $5.26 billion of oil over the next six months to purchase food, medicine and humanitarian goods. The "oil for food" arrangement had been renewed for shorter periods in recent weeks as Russia and the United States sought to use it as a lever in the broader talks.

Baghdad halted oil exports to protest the stopgap extensions but indicated that it would resume pumping if the council passed the six-month renewal. Iraqi oil exports are expected to resume in mid-December.