A Defense Department spokesman, confirming yesterday that the Pentagon favors letting Egypt help produce U.S. warplanes for Mideast and Persian Gulf countries, said "the earlier the better" when asked when this might take place.

Spokesman Benjamin Welles added that Israel would face "no security problem" if Egypt went into fighter production with U.S. help. The planes to be produced in Egypt under administration plans would be either the Northrop F5G or General Dynamics F16/J79 which, although high-performance jets, are not considered a match for the McDonnell Douglas F15 flown by the Israeli air force.

Welles said U.S. aerospace firms, with administration approval, "have been discussing coproduction with Egypt" of the F5G and/or the F16/J79, both of which are known as FX (fighter export) fighters. The idea is to give emerging nations a hot fighter but one slightly inferior to the best in the U.S. and North Atlantic Treaty Organization inventories.

Finding the money needed to gear up Egyptian industry to produce FX fighters is the big problem confronting the coproduction plan, he said. The administration does not intend to lend Egypt the money, and Egypt does not have the funds, he said.

Although Welles did not say so, other Pentagon officials estimated that between $1.5 billion and $2 billion would be needed to put Egypt into modern warplane production. These officials added that Saudi Arabia is their prime hope for bankrolling Egypt.

Welles said the administration has "not been urging" Saudi Arabia to commit the funds to Egypt. "We have not been suggesting where the financing should come from," he said.

Administration officials told The Washington Post Monday that the administration "is urging Saudi Arabia to lend Egypt as much as $2 billion to manufacture U.S. warplanes for friendly countries in the Middle East and Persian Gulf."

The Saudi ruling family is extremely sensitive to any suggestion that the United States is telling it what to do, and administration leaders have gone to great lengths to avoid offending Saudi sensitivities on this point.

During the briefing yesterday, Welles was asked who other than the Saudis and the United States could provide such funding for Egypt. His reply was a smile.

State Department spokesmen said Northrop and General Dynamics have been authorized to discuss with Egypt coproduction of their FX fighters. "The U.S. government does not favor one over the other," the department said in a prepared response.

In a separate development, the department, which earlier had denied several requests by General Dynamics to brief Bahrain on its F16/J79 FX fighter, gave such approval Monday. Northrop received permission from the department last month to brief Bahrain on its F5G, according to company spokesmen, and Bahrain has agreed to buy four F5Gs.