New Peace-Seeking U.N. Mission for Vance: Nagorno-Karabakh : Caucasus: Envoy is asked to augment several other diplomatic attempts to end the hostilities.

Secretary General Boutros Boutros-Ghali on Friday called on former Secretary of State Cyrus R. Vance once more to work his diplomatic skills on a stubborn crisis--sending him this time to bloodied Nagorno-Karabakh in the former Soviet Union.

Vance, 74, who played a role in fashioning the cease-fire in Yugoslavia, will probably leave Monday for the largely Armenian-populated enclave within Azerbaijan, visiting the Azerbaijani capital of Baku and the Armenian capital of Yerevan, as well.

Perhaps 1,500 people have died in fighting between Armenians and Azerbaijanis in the last four years, mainly in the disputed enclave.

A cease-fire in Nagorno-Karabakh was announced during the day.

But, like others in the past, it seemed to dissipate quickly. Spokesmen for both Armenians and Azerbaijanis soon reported firing on both sides Friday.

The dispatch of Vance to the troubled area of the Caucasus Mountains marked the first official move by the United Nations to try to deal with the crisis. The neighboring states of Armenia and Azerbaijan joined the United Nations only 10 days ago alongside six other republics of the former Soviet Union.

The Vance mission will augment several other diplomatic attempts to mediate and moderate the hostility.

Czechoslovak Foreign Minister Jiri Dienstbier, in his role as president of the Conference on Security and Cooperation in Europe (CSCE), is also heading to Nagorno-Karabakh. Accompanied by officials from the International Committee of the Red Cross, Azerbaijan Deputy Interior Minister Natik Talibov left Baku for Nagorno-Karabakh, where he planned to talk with local Armenian leaders.

Turkish Prime Minister Suleyman Demirel is also trying to ease the conflict. And the French government has offered to host a peace conference of all those involved. Diplomats meeting in Finland proposed an international conference under the auspices of the CSCE.

In a cable to Dienstbier, Boutros-Ghali said he was sending Vance to gather information about the problems and was not trying to supplant European efforts in any way.

“Please be assured . . . that my purpose in sending Mr. Vance on this fact-finding mission is to complement regional efforts in search of peace,” the secretary general said.

Boutros-Ghali, who had already sent telegrams to the presidents of Armenia and Azerbaijan calling for “maximum restraint,” told the president of the CSCE, “The grave situation in that region calls for a concerted effort to prevent further violence and to create conditions for a peaceful solution.”

Vance, who made six trips as Boutros-Ghali’s special envoy to Yugoslavia, is credited with playing a hand in working out a cease-fire there that has been in place since early January.

Although neither side in the Caucasus fighting has filed any official request for U.N. involvement, both have said they would welcome it. In fact, Azerbaijani Foreign Minister Husein-Aga Sadykhov told reporters at the United Nations last week that he would like to see U.N. Blue Helmet peacekeepers stationed on the border between the two countries.

Meanwhile, the joint armed forces command of the Commonwealth of Independent States (the former Soviet Union) decided to evacuate all its military posts on the border between Armenia and Azerbaijan. The command acted after one soldier was killed by Azerbaijani shells and another was taken hostage in an Azerbaijani settlement; 10 other soldiers, kidnaped by Armenians a few days ago, were released Thursday.

On Thursday, Armenians fired about 100 rockets and artillery shells into Agdam, an Azerbaijani city about three miles outside Nagorno-Karabakh. Estimates of the deaths ranged from 10 to 25. Armenians also overran a military post outside Agdam, killing six soldiers.

In other reports of unrest in the former Soviet Union:

- Forces loyal to ousted President Zviad Gamsakhurdia threatened to decapitate a top leader of the National Guard in Georgia. The officer was captured when his government helicopter was shot down by pro-Gamsakhurdia forces.

- Officials reported that two people were killed in a battle in eastern Moldova between police and separatists.