Yugoslavia's ruling Communist League today offered a grim picture of growing economic and political troubles in the opening report of a national Congress shadowed by concerns about the party's declining authority.

Vidoje Zarkovic, president of the party Presidium, read a lengthy statement that said excessive state control, rivalry among Yugoslavia's eight political jurisdictions and the weaknesses of Communist leadership had deepened severe economic stagnation and contributed to growing tensions among the country's various national groups.

"We are face to face with stagnation in development, with weakening unity in the Yugoslav community and in the League of Communists of Yugoslavia, with greater distortions and departures from proclaimed aims," Zarkovic said. The party, he said, "has not pursued a timely and proper struggle against these tendencies."

The grim assessment appeared intended to reflect the "great dissatisfaction" it reported among Yugoslav society and to prepare the public climate for painful new stabilization measures under a newly inaugurated federal government.

However, the report and accompanying draft resolutions for the four-day Congress suggested no major changes in Communist strategies for managing the crisis or moves toward major political reforms.

Instead, the leadership's report called for the strengthening of Yugoslavia's unique system of worker self-management of enterprises through the checking of both bureaucratic "statists" in the various republics and liberals seeking a move toward capitalism.

The party, it said, must seek "a change in its present position in society," ceasing to act itself as a bureaucratic power, and offer "genuine programs instead of papers and empty appeals."

Political activists and western diplomats here said the relative lack of new initiatives at the Congress, held only once every five years, reflected the progressive weakening of Yugoslavia's national leadership in the six years since the death of postwar leader Tito.

Because of the power of Communist organizations in each of Yugoslavia's six republics and two autonomous provinces, most major leadership decisions were determined in congresses in the republics last month. Radical changes of policy, in turn, have been blocked by the need of the various authorities to agree on "consensus" positions despite sharp differences on both economic and political policy.

"What is typical," said Milovan Djilas, the country's best-known dissident, "is the discontent of all the participants -- but without any clear ideas, any common theme."

The opening of the Congress followed a week in which government officials did announce new measures to control the country's two most threatening problems: growing tension between rival Serbian and Albanian populations in the impoverished southern province of Kosovo and runaway inflation.

Economic reports for the first five months of this year showed inflation reaching an annual rate of 85 percent, the highest in Europe, while a decline in exports threatened financial arrangements for the payment of Yugoslavia's $20 billion foreign debt.

At the same time, government and party authorities have been confronted with volatile public emotions in the country's largest republic, Serbia, over the treatment of Serbs living in Kosovo, which is dominated by ethnic Albanians. Groups of Serbs from Kosovo have demonstrated in Kosovo and organized two trips to Belgrade this year to demand protection from what they say are violent efforts by Albanians to drive them out of the province.

Party authorities last month purged the Communist leadership in Kosovo of leaders perceived as sympathetic to the nationalist Albanians. Last week, the government endorsed tough new penalties for the illegal sale of property, and the investigation of cases of vandalism, bombings and other disturbances.

On the economic front, government officials revealed the first of three planned packages of new measures Monday. The proposed steps, which must be approved by the Parliament or legislatures in the republics, include controls on about one-third of exports.

The measures represent the first political test for new Prime Minister Branko Mikulic, who took office May 15. Mikulic, a 57-year-old veteran administrator from Bosnia, was chosen by party leaders to head the government in the hope his aggressive style would provide some of the national leadership the country has been missing.

Diplomats and party officials said both the economic and Kosovo initiatives, while significant, represented only a partial response to the problems and would probably be followed by more drastic action later this year. In this context, they said, the party Congress could serve to build up the political momentum necessary to implement tough measures despite the factionalism and resistance of entrenched local authorities. Zarkovic singled out the fragmentation of authority as a principal cause of the crisis.