Premier Bulent Ecevit emphasized today that the use of Turkish airspace to monitor Soviet compliance with the new strategic arms limitation treaty to be signed next month depends on Moscow's approval.

Commenting on an American request to monitor Soviet missile tests from U2 spy planes flying over Turkey, Ecevit said; "Turkey is prepared to help make SALT II work, but we cannot provide the support requested unless both parties to the agreement have the same understanding."

Western diplomats said it was unlikely that the Soviet Union would endorse the plan, even though Ecevit said he had been assured by U.S. officials that the U2s would be used only to verify SALT and not to "spy" on the Soviet Union.

Ecevit said U.S. officials had also todl him that verification of SALT II by satellite was inadequate following the loss of U.S. bases in Iran, and impractical from American radar stations in Turkey because of geographical obstacles.

But he insisted that "while we support would peace we would not want to damage our ties with out neighbors or jeopardize our own security."

He said he had informed the U.S. government of Turkey's "reservations."

Turkish sources said U.S. officials had told them that the U2 flights would originate from Cyprus, and they were necessary to win ratification of SALT II by American senators concerned about effective verification.

The Turks, however, are very touchy about U2s ever since CIA pilot Francis Gary Powers, shot down in 1960 during a spy flight over the Soviet Union, revealed he had taken off from an American base in Turkey.

The incident strained relations between Turkey and its huge northern neighbor, the Soviet Union.

In recent years, however, the two countries have moved to improve their ties and last year signed a friendship treaty.

"Turkey is continuing relations of mutual cooperation with her neighbors to strengthen its own security and the security of the region," Ecevit said today. "We will avoid taking any steps that would case a shadow on our efforts."

Opposition leader Suleyman Demirel, commenting on the U2 plan, said it would place Turkey "in front of the gun barrel" on any future East-West confrontation.