Turkey demanded increased American economic and military aid today in exchange for extending an agreement that allows the United States to use bases in this country to monitor Soviet missile tests.

These bases have become increasingly important since the closing of sophisticated monitoring stations in Iran that allowed the United States to keep tabs on the Soviets. The Carter administration is anxious to replace the Iranian stations with some in Turkey-including two with special scanning equipment-to assure Congress that the Soviets will not get away with cheating on the SALT II agreement that is expected to be signed next month.

Four hours of talks today between Turish Prime Minister Bulent Ecevit and U.S. Turish differences about the base agreement, which expires in October.

American officials expressed optimism that an agreement eventually would be reached despite the present differences. Ecevit said his talks with Christopher should help iron out "technical" difficulties.

[State] Department officials in Washington said Christopher did not expect to walk away from his visit to Turkey with a base agreement. If one is not signed by October, U.S. officials expect the deadline ot be waived. "I don't think the Turks want to close the bases down again," a U.S. displomat said.

Underlying the dispute is a deepseated Turish resentment about what officials view as U.S. slights over the years. Turish officials complain that the United States cares about them only whenit needs bases, but fails to consult with them on general defense matters.

Moreover, the Turks feel they are not considered an economic partner of the Western powers and have not received enough help during the worst economic crisis in their history.

The military bases, which were shut down by the Turks in August 1975 in retailation to the U.S. congessional arms embargo imposed on Turkey following its 1974 invasion of Cyprus, were allowed to resume operations temporarily last September after the embargo was lifted.

The Turks set a one-year deadline for working out a permanent agreement covering the bases, to include increased economic and military aid to Turkey and assistance in setting up its own arms industry so that it would no longer be dependent on the United States for weaponry.

The Turks say they need a total of $15 million in Western grants, credits and investment over the next five years to rebuild Turkey's shattered economy and reequip its armed forces.

"Defense cannot be separted from economic issues," Sukru Elekdag, Turkey's ambassador designate to Washington, told Christopher in an airport arrival statement. "We believe cooperation between the two countries should include economic as well as other fields."

The Senate Foreign Relations Committee yesterday left intact $100 million in military aid for Turkey while trimming $109.6 million from the Carter administration's total request. That $100 million is in addition to the $50 million in military credit sales approved last week to bolster the Turkish armed forces.

[The United States makes no bones about the reason for giving military assistance to Turkey. In a justification to Congress for selling $111 million of military equipment to Turkey, the Pentagon said the sale "allows for the operation of valuable U.S. intelligence and communications facilite"]

Although Christopher gave Turkey no firm commitments on increased U.S. economic aid, Ecevit said the U.S. official promised to try to speed up a plan by Western powers to provide some crash aid to Turkey to help it out of its immediate difficulties.

Such a plan was approved in principal by the leaders of the United States, West Germany, France and Britain following the loss of American bases in Iran, but so far nothing has come of it.

The loss of the Iranian bases has increased the strategic value of U.S. installations in Turkey. By far the most important of these are the ones at Pirinclik, 180 miles from the Soviet border, where radar antennas pick up Soviet missiles on test flights, and at Sinop, on the Black Sea, where listening devices monitor Soviet military communications missile test data. CAPTION: Picture, BULENT ECEVIT . . . asks more U.S. aid; Map, no caption, By Dave Cook-The Washington Post