Prime Minister Michael Somare won an impressive victory in the first elections held by newly independent Papua New Guinea, according to results announced today. The outcome brings immense relief to nearby Australia and to American diplomats in the area.

Papua New Guinea became an independent nation in 1975 and Somare, now 39, was virtually appointed prime minister at the time by Australia, which had governed the huge, primitive multi-island territory since 1918.

He was handpicked for the job by Australian diplomats and recognized as long ago as the late 1960s by the United States as a man who could bring the islands into stable, cohesive independence.

In 1970, Somare toured the United States under a State Department leadership grant and if friendliness toward the United States was the object of the grants, it has paid off in the case of Samare.

Throughout a campaign that began nearly a year ago because of the physical difficulty of communicating with the 700 culturally diverse and geographically separated tribes on the islands. Samare emphasized his determination to keep Papua New Guinea a united country.

Somare's Pangu Party is allied with the People's Progress Party led by Deputy Prime Minister and Treasurer Julius Chan and personality cult independents who won seats because they supported Somare. This alignments gives prime minister and unexpected majority of at least 60 of the 108 seats in Parliament.

Somare's victory in elections held over the past month apparently has ended, at least for the three-year life of his new government, the prospect of Papua New Guinea disintegrating into several states, a prospect that had the military government of Indonesia's President Suharto concerned, the Australian government worried and the United States nervous.

Because of the diversity of the tribes in the country, many observers through that the national elections would create a Parliment of tribal independents.

Instead, Somare managed to implant his personality on the electorate and won a convincing victory.

His power confirmed, Somare is expected to strengthen his ties with Australia and the United States, the two nations that recognized his leadership potential nearly a decade ago and were the only two countries to establish direct diplomatic ties with Papua New Guinea the day it became an independent nation.

The huge island of New Guinea, hovers over Australia's north representing either a giant wall barring the way to Asia's hordes - or, in the deep psyche of Australian's, an inviting land bridge for them.

The western half of the island, formerly a Dutch colony, like Indonesia, acquired by Jakarta in 1962 with the approval of Washington and the reluctant blessing of Canberra.

At about the same time, Australia granted a degree of self-rule to Papua New Guinea, the eastern half of New Guinea and adjoning islands, which it had administered as the heir of British and German colonial empires.

With a memory of Indonesia's invasion of the Portuguese colony of East Timor in 1975, the Australian government was nervous about any possibility that Indonesia would try to extend its border eastward if this week's election had split Papua New Guinea. The eastern half of New Guinea includes 85 per cent of Papua New Guinea's land.

American diplomats in the area were concerned because such a result would have deepened the district between Canberra and Jakarta already created by the Indonesian takeovers of West New Guinea and East Timor - a distrust between two nations that are allied to the United States.

Somare's victory capped months of extensive diplomatic travel. Since the beginning of the year, he has visited China, Indonesia, Australia and Britain, both to stabilize his new country's relations with nations important to it and to impress his country's 2.5 million people that he was equipped to be its leader.

The travel apparently paid off.

Papua New Guinea is one of the most primitive nations on earth with huge areas still unexplored, more than 600 languages, internal communications that amount to no more than erratic radio, and cloud-filled valleys reachable mainly by World War II Dakotas and light aircraft.

Is is also enormously rich in natural resources. It is lush with timber, copra, cocoa: has one of the world's biggest copper mines in Bougainville, and is widely believed to be rich in oil.

Other than the capital city of Port Moresby on the southern coast of the main island, where the nation's only highway ends on the outskirts. Papual New Guinea consists of remote villages and tribes - some less than a generation away from head-hunting and canniballism and mosh still living in a primitive stone age.