Senate Majority leader Robert C. Byrd (D.W. Va.) said yesterday that the Carter administration will not formally notify Congress of its controversial intention to sell warplanes to three Mideast nations until the Senate has completed action on the Panama Canal treaties.

Speaking at his weekly news conference, Byrd said he had discussed the controversial "packago deal" of warplane sales in a Friday telephone conversation with Secretary of State Cyrus Vance. He advised Vance to postpone the formal notification, and the secretary agreed, Byrd said.

The administration's plan is to sell advanved F15s to Saudi Arabia, comparble F16s to Israel, and lesser F5E's to Egypt, but to make all three sales conditional on each other - hence a "package." Israel and its American supporters bitterly oppose the package idea and will apparently fight it in Congress.

Congress has 30 days after notification of a proposed arms sales to pass a resblution of disapproval blocking it. Byrd said he told Vance the Senate could not properly consider the question while the Canal debate is still going on.

The majority leader did not predict when a final vote might come on the second cansl treaty. He said he hoped it would be early April, and he renewed his promise to cut the Senate's Easter recess from 10 days to five if treaty opponents refuse to agree to a date for a final vote.

Byrd declined to make any optimistic claims about the outcome of the second treaty vote, and said it would be another tought fight. The Senate approved the first Panama Canal Treaty Thursday by 68 to 32.

Byrd said he though it was possible that the second treaty - which spells out terms for turning over the canal to Panama between now and 2000 - might be amended or changed as the first one was.

He defended the reservations the Senate added to the first treaty - which have alarmed Panamanian officials - as changes that clarified and made specific certain sections of the treaty.