The U.S. Navy is fighting an Israeli proposal to commission a U.S. shipyard to build three diesel-electric submarines, in part because Navy officials fear that Congress then would pressure them to buy diesel subs instead of costlier nuclear-powered boats.

Navy Secretary John F. Lehman Jr. has made clear to several shipyards dependent on Navy business that he opposes the Israeli request, according to government and industry officials. Lehman's concern is that once a U.S. shipyard began building diesel subs, congressional pressure on the Navy to buy diesel subs -- already quite strong -- would become irresistible.

Nevertheless, the Israeli proposal is under consideration, according to U.S. officials. Defense Secretary Caspar W. Weinberger is likely to discuss Israel's submarine needs when he visits Tel Aviv next week.

Lehman and other officials have raised other questions about the Israeli proposal. U.S. officials said that new submarines are extremely expensive and Israel might be able to satisfy its security needs by buying used subs or in some other way.

In addition, Lehman has argued that an Israeli order would divert welders and others with skills needed for U.S. submarine programs. Two U.S. companies -- Newport News Shipbuilding and Drydock Co. of Virginia and the Electric Boat Division of General Dynamics Corp. in Connecticut -- are in the submarine business, both building nuclear-powered subs only.

Diesel-electric submarines are smaller and far less expensive than the nuclear-powered ships in the U.S. Navy. A diesel submarine would cost about $100 million; the U.S. Navy pays between $500 million and $700 million -- depending on how costs are figured -- for each nuclear-powered, Los Angeles-class attack submarine.

The Navy wants to buy 20 Los Angeles-class submarines in the next five years and then begin building a new class of nuclear-powered attack submarines, whose mission is to search out and destroy enemy submarines and ships. Almost every time Lehman appears before a congressional committee to justify his budget, someone asks why he cannot buy diesel submarines, which can operate quietly and stealthily under water.

Lehman acknowledges that diesel-electric submarines can be effective, but he says they are not suited to U.S. missions, which require submarines to submerge for months without refueling.

Once a shipyard began producing diesel submarines, it would not want to stop after filling Israel's order, Navy officials fear. Strategic arguments then would be bolstered by political pleas from the company and employes.

Israel owns three British-built diesel-electric submarines and would like to buy three more, perhaps with a German design. But it does not want the ships built in West Germany because that could give the Germans justification for selling arms to Saudi Arabia, U.S. officials said.

In addition, Israel would have an easier time using U.S. military aid for vessels produced in this country. The Israelis have approached several shipyards that have expressed interest, given the depressed state of shipbuilding, officials said. But the companies would be reluctant to anger their largest customer, the U.S. Navy.