The Reagan administration, in a first for U.S.-Israeli relations, will lease warplanes from Israel to help train Navy pilots in dogfighting, Pentagon officials said yesterday.

A contract expected to be signed by the Navy today calls for the United States to lease 12 used Kfir C1 fighters at no cost and to pay Israel Aircraft Industries $68 million during 3 1/2 years to maintain them in this country.

In other firsts, the Navy will send pilots to Israel to be trained on the Kfir while Israel will send mechanics and other specialists to the Naval Air Station at Oceana, Va., to maintain the supersonic aircraft for the 3 1/2-year period.

The number of Navy pilots to go to Israel is being debated, Navy officials said yesterday. One idea is to send four instructor pilots and have them train other Navy pilots in the United States. The other proposal calls for sending an entire Navy squadron to Israel for training.

Election-year politics hangs over the question, sources said. The Reagan administration wants the Navy training in Israel to be visible enough to impress Jewish voters with President Reagan's commitment to a strong U.S.-Israeli military relationship. But sources said it did not want the presence of the American military in Israel to loom larger in the eyes of friendly Arab states than it is.

Navy pilots from the VF43 adversary training squadron in Oceana would need about two weeks in Israel to be checked out on the Kfir.

Israeli Aircraft Industries plans to send 15 Kfir specialists to Oceana and to flesh out the maintenance team by hiring 60 to 70 more people in the United States.

The Israeli Air Force employs the Kfir as its workhorse fighter bomber but relies on the more-advanced F15 and F16 fighters supplied by the United States for its cutting edge in aerial combat. Navy pilots in VF43 at Oceana will fly Kfirs to simulate Soviet MiG21 fighters against Navy pilots flying F14s.

At its East Coast adversary squadron at Oceana, the Navy currently flies the subsonic Navy A4 attack plane to simulate the old Soviet MiG17 fighter and the Air Force F5 to simulate the MiG21.

Advantages of leasing Kfirs, Navy officials said, include their speed and versatility. The Kfir can achieve twice the speed of sound and therefore about twice the speed of the F5. It can carry the radar and other gear that modern versions of the MiG21 would bring to battle against U.S. aircraft.

The first three Kfirs are expected to be delivered to Oceana in six months; the remaining nine would follow at the rate of three a month. Navy officials stress that the Kfirs are an interim step to upgrading its adversary squadrons for advanced training in dogfighting against Soviet aircraft.

The Navy's effort to buy 24 planes from U.S. companies to simulate Soviet fighters is in a political briar patch. The contenders are General Dynamics, with a simplified version of its F16; Northrop, with its new F20 fighter, and Vought Corp., which would use MiG21 airframes purchased from China.

Some members of Congress, in considering the Pentagon's fiscal 1985 authorization bill, have tried to impose conditions on the adversary program that critics say jeopardize its future.

Navy officials said they had turned to Kfirs to ensure that training against advances in the Soviet aerial threat would not be hampered by a lack of modern aircraft. The Soviet advances include missiles that, like U.S. counterparts, can be fired while planes approach each other head-on.