A slip of the tongue by Prime Minister Menachem Begin yesterday may have pinpointed the Arab country that Israel believes will eventually get U.S.-made F15 jet fighters from Saudi Arabia in case of a new Middle East war.

Israel has repeatedly condemned the sale of the sophisticated planes to the Saudis, saying it has reliable information Saudi Arabia will transfer them to one of the Arab confrontation states if a war starts. But Israel has refused to say which state - Egypt, Syria or Jordan - it expects to get the planes.

On ABC's Issues and Answers yesterday, Begin said:

"We have it on a good source and a good basis that the Saudi Arabians already promised a certain Egyp - a certain Arab state" that it would get the F15s in wartime.

Asked moments later, "Is that state Egypt?" Begin replied, "I can't say what is the state. I only can state again it is an Arab state and a confrontation country."

Begin said the sale of the F15s to Saudi Arabia and the sale of F5Es to Egypt pose a "grave danger" to Israel and he said the sale of planes to the Arab countries should not be linked with new arms supplies for Israel, as Carter has proposed.