Yugoslavia’s Breakaway States Warned : Europe: Economic ostracism is a threat. Top U.S. and European officials urge unity and a peaceful solution.

BERLIN — Top foreign policy officials of the United States, Canada and all European nations Wednesday urged Yugoslavia to protect its unity, warning that if its constituent republics insist on independence, they could lose international economic and political support.

The caution, issued by the 35-member Conference on Security and Cooperation in Europe, marked the first time that any European organization has gotten involved in a controversy involving one of its members.

And it reflected the first efforts by the CSCE--which East European states have hoped would become their security mantle--to establish itself as something more than a debating society.

In a statement referring to Yugoslavia, all the CSCE foreign ministers called for a “peaceful solution of the current crisis.”

It added that, if the Balkan state remains unified, “the international community would stand ready to assist Yugoslavia’s efforts to transform itself economically and politically.”

A German diplomat here described the statement as a veiled threat to independence-minded Slovenia and Croatia that, if they break away from the 73-year-old Yugoslav federation, they would face political isolation and economic ostracism.

“We are trying to send a message,” the German diplomat said, “to ethnic groups throughout Europe that we appreciate their striving for forms of autonomy--but not at the expense of breaking up nation states.”

Although directed specifically at Yugoslavia, the message also seemed to encompass other ethnic disputes, such as those in the Soviet Union, Czechoslovakia and other parts of Europe.

A senior U.S. official attending the talks said the statement was a demonstration of the increased muscle of CSCE--reorganized last year after 15 years in which it had no bureaucracy or formal organization of its own.

The official added that the conference is expected to agree before it concludes today to establish a new emergency procedure that would permit a handful of members to call a meeting to consider situations that might endanger peace.

Earlier Wednesday, Albania--for decades a hard-line Stalinist bastion--was admitted to conference membership. CSCE now includes every country in Europe, including tiny states like the Vatican and San Marino. The United States and Canada are also full members, despite the group’s European orientation.

In applying for membership, Albania promised to adopt the CSCE’s overall principles--mutual security, economic freedom and human rights.

Albania, which installed a new non-Communist government last week after 47 years of Communist rule, also agreed to accept a CSCE fact-finding team to determine if its once-dismal record of human rights violations has improved.

CSCE, often referred to as the Helsinki process because it was created in the Finnish capital in 1975, is one of the few international organizations to successfully span Cold War divisions. However, with much of Eastern Europe adopting democratic reforms, CSCE is now envisioned as the bridge between the affluent nations of the West and the struggling East.

The organization operates by consensus, meaning that a single member can veto any action. However, U.S. officials said the Yugoslavia declaration shows that the organization can address sensitive matters despite the unanimity requirement.

Yugoslav Foreign Minister Budimir Loncar approved the statement. This is not surprising because he represents the country’s central government, which supports continued unity.

U.S. officials said that no attempt was made to obtain the approval of Slovenia or Croatia.

However, Secretary of State James A. Baker III plans to confer with officials of all six of Yugoslavia’s constituent republics, as well as with leaders of the central government, when he visits Belgrade on Friday.

Meanwhile, the Soviet Union vetoed a proposal, backed by the United States, to give the Baltic republics of Estonia, Latvia and Lithuania official status as CSCE observers. The three republics, annexed by force to the Soviet Union in 1940, have asserted their independence.

Foreign ministers of the Baltic republics attended the conference as guests of Germany and some other delegations.

Unity Urged

While Albania became the newest addition to the CSCE, the members cautioned Yugoslav republics to stick together.