U.S. Presses Case for Aid to Soviets : Economy: It urges allies to devise a plan to help Moscow on debt payments.

As Soviet officials began their first talks with top economic policy-makers of the leading industrial democracies, the United States was having difficulty persuading most of its chief Western allies that now is the time to take action to avert a Soviet payments crisis, sources said Saturday.

Soviet economist Grigory A. Yavlinsky, deputy chairman of the Committee for Management of the National Economy, presented the Westerners with an economic assessment and plan during the meeting. Yavlinsky declined to comment on the Soviet proposal and said he would make more details available after the sessions conclude today.

“It was very useful,” U.S. Treasury Secretary Nicholas F. Brady told reporters after the session.

To prepare for their meeting with the Soviets, the Western officials had held more than seven hours of talks earlier Saturday. The United States was said to have lobbied hard to persuade its other allies to come up with a plan for helping the Soviets keep up with the payments on their debt of almost $70 billion.

While that is not a large debt for a country the size of the Soviet Union, much of it is coming due relatively soon. By some estimates, Moscow could be facing a shortfall of more than $5 billion in the next few months.

But officials said that only Japan and Canada are convinced that a crisis is looming.

The European members of the so-called Group of Seven--Germany, Britain, France and Italy--continued to argue for delay, saying that it is far from clear that the Soviets will need any aid at all in paying their debts. Instead, they emphasized what they said is a need for food and other humanitarian assistance to get the Soviets through what could be a difficult winter.

“The most important parameter we agreed to this afternoon is that we should listen to what the Soviets have to say,” Treasury Undersecretary David Mulford told reporters. He and others have noted that the G-7 still lacks much of the information it needs regarding both the size of the problem and the resources the Soviets themselves have at hand.

Yet before meeting with the G-7, the Soviets moved toward resolving perhaps the trickiest question--the economic relationship between the central government and independence-minded republics--when nine of the 12 republics agreed Friday to sign an agreement to form an economic union.

“That’s regarded as an important step forward by everybody,” Mulford said.

Only part of the Soviet delegation arrived in time for the opening dinner session of their discussions with the G-7, forcing the economic ministers and central banks to extend the talks into today.

Germany, in particular, is wary of any action to alleviate the payments pressure on the Soviets, because a large share of the Soviet loans are owed to German bankers. The United States holds only about $1 billion in loans to Moscow.

The G-7 meeting is a prelude to this week’s annual meetings here of the International Monetary Fund and World Bank.

The Soviet Union has applied for membership in both organizations, but thus far it has been granted only a “special associate” status. That gives it access to IMF and World Bank expertise and advice in instituting economic reforms but not to any of either institution’s considerable financial resources.

The Soviet Union spent decades denouncing the very institutions that it now seeks to join, and its participation in the meetings here reflects how drastically its philosophy has shifted in the wake of the failed August coup.

Before the arrival of the delegation led by Yavlinsky, the G-7 finance ministers and central bankers issued a communique that showed few of the disagreements that have punctuated many of their past meetings.

In large measure, this apparent accord on such issues as interest rates and currency exchange rates could reflect how their concerns over the Soviet Union have come to dominate their agenda.

They noted that worldwide growth has been weak but said that recovery is under way in the United States and Canada, while Britain is “moving toward recovery.”

They raised the prospect that, as economic vigor returns, so might widening trade deficits. That statement clearly referred to the potential for further growth in Japan’s domination of the worldwide export market.