A high-level U.S. delegation that flew hurriedly to Ankara Tuesday in an effort to soothe troubled Turkish-American ties, met twice with Premier Bulent Ecevit yesterday.

Ecevit said the delegation, headed by Deputy Secretary of State Warren Christopher, brought proposals resulting from a "new political decision by President Carter concerning Turkish-American relations."

Ecevit did not elaborate. But informed sources said the delegation carried proposals for resuming American military aid to Turkey in response to Turkish charges that the Carter administration was vacillating on ending the arms ban.

This was indirectly confirmed by Turkish Foreign Ministry spokesmen, who said the Ankara talks were a continuation of a meeting in January between Ecevit and Secretary of State Cyrus Vance, at which they agreed to review the two countries' defense cooperation accord.

The sudden arrival of the U.S. delegation, after two months inactivity on this front, followed statements by Ecevit that Turkey could no longer depend on the United States and NATO for its defense.

Ecevit, a left-leaning Social Democrat, has set a May 30 deadline for the lifting of the arms embargo imposed by the U.S. congress following the 1974 Turkish invasion of Cyprus.

He had indicated he might boycott the Washington NATO summit, set for that date, and follow a more neutral role in world politics if congress does not act by then.

The three-year-old military aid cut-off has seriously impaired Turkey's defense capability and contributed to the country's chronic economic crisis by forcing the Ankara government to divert scarce foreign exchange to cash arms purchases.

The Ford administration initialed an agreement with Turkey in March, 1976, calling for $1 billion in military aid in exchange for reopening U.S. bases, closed by the Turks in reprisal to the arms ban.

Senior U.S. legislators, who previously had tied approval of the accord to settlement of the Cyprus problem, have indicated recently they would support its passage.

But Vance, in an apparent turn-around earlier this month of the previous administration policy, tied lifting of the ban to Cyprus peace moves and sparked a further deterioration in Turkish-American ties.

Observers said Christopher's hurriedly arranged mission was an attempt to reassure the Turks of the Carter administration's commitment to early resumption of arms sales and military aid.

Ecevit was expected to press not only for lifting of the embargo but also for an increase in the promised military aid on grounds of the declining value of the dollar and increased defense costs.

But he himself said after meeting with Christopher that it was too early to say whether the embargo would be lifted.

Commenting on the Christopher mission, the Soviet news agency Tass said it was a U.S. attempt "to prevent Turkey's departure from NATO and the pursuance of a more independent foreign policy."

"Jointly with NATO allies, the U.S.A. is now stepping up pressure on Ankara, resorting to lavish promises of financial economic and military aid," Tass said.

The Soviet Union, at which U.S. bases in Turkey are mainly directed, has recently pledged $1.2 billion economic aid to the Turks. In exchange, they are seeking a friendship treaty with the Turks.