In an unusual public statement on the Cyprus dispute, the State Department yesterday called new Turkish proposals "a positive contribution" toward resuming the stalled Greek-Turkish peace talks in that island country.

The statement appeared to be an attempt to prod the Greek side into new negotiations, thereby bolstering the Carter administration's uphill struggle to end the congressional embargo on U.S. arms to Turkey.

Congress imposed the embargo in 1975 after Turkish forces, armed with U.S. weapons, invaded Cyprus. Turkey continues to occupy between 35 and 40 percent of the island, which has an 80 percent Greek population.

Despite fierce opposition from the Greek-American community, the administration has asked Congress to repeal the embargo because Turkey has threatened to reduce its contribution to North Atlantic Treaty Organization defenses in the Mediterranean.

The administration argues that lifting the embargo offers the best hope for settling the Cyprus dispute because Turkey has warned it will not negotiate nor withdraw its troops under overt U.S. pressure.

It was against this background that a State Department spokesman, Tom Reston, began a routine press briefing yesterday by reading the statement studded with praise for the latest Turkish proposals.

"We consider it a very constructive and forthcoming one which indeed should make a positive contribution toward resumption of the Cyprus negotiations," Reston said.

He was referring to proposals that Rauf Denktash, leader of the Turkish Cypriot community, presented to U.N. Secretary General Kurt Walsheim on Monday in an effort to get the peace talks resumed under U.N. auspices.

The State Department also distributed a statement by Denktash, describing his proposals as a revised version of a plan put forward by the Turks on April 13. The earlier offer has been rejected by the Greek side as an inadequate basis for returning to the negotiating table.

In their latest proposals, the Turks maintain their position that Cyprus essentially be divided into two internally self-governing ethnic communities with a joing legislature and a limited executive power that would handle such functions as foreign affairs and defense.

However, Reston said the administration regards the newest plan as differing from the April proposals. He stressed Denktash's pledge to negotiate "with an open mind and in a spirit of conciliation and flexibility."

The department statement also underscored elements of the proposals aimed at dealing with the Cyprus refugee problem. In the wake of the Turkish invasion, thousands of Greek Cypriots abandoned their homes and fled from the Turkish-occupied part of the island.

The statement noted that the Turks are prepared to consider "significant geographical readjustments that would enable a considerable number of Greek Cypriots to resettle" and, even before a settlement is reached, to allow 30,000 to 35,000 former Greek Cypriot residents of Varosha, the new part of Famagusta, to return.

In addition, the statement added, Denktash proposed the possibility of reopening the long-closed Nicosia airport to civilian traffic from both sides and "other concrete steps for healing the wounds of the past."

Asked whether the statement was aimed at influencing the impending congressional debate on the Turkish embargo, Reston said: "We are not offering a specific message to Congress."

However, department sources noted that the four principal figures in the dispute - Denktash, Cyprus President Spyros Kyprianou, Greek Prime Minister Constantine Karamanlis and Turkish Prime Minister Bulent Ecevit - will all be at the United Nations this week.

For that reason, the sources said, the administration felt that the new proposals offered the possibility of getting the contending sides together in a way that might influence Congress favorably.