Israeli Prime Minister Menachem Begin says the United States "must now consider very seriously" whether to station conventional forces in the Middle East and in "every region where there is a possibility of Soviet expansionism."

Sure forces would be "ready in cases when it is necessary to stop this expansionism," Begin said in an interview taped before he left Washington last week. The interview was telecast yesterday on "Issues and Answers" (ABC, WJLA).

"You know, you should see the map," Begin said. "Now, the Soviet Union is in Afghanistan, and through Baluchistan, they can reach the Indian Ocean in no time, and there is no force to stop them. Iran itself could become a communist state with the Tudeh Party, the best organized group . . . Waiting."

Citing the long border between Iran and the Soviet Union, the prime minister said that in such a situation "all of the atomic weapons and big ships are completely irrelevant."

Begin dismissed as unsatisfactory the possibility of the United States bringing in conventional forces from afar, "because to bring them from California, even by planes, will take days, and by ships it will take weeks."

He said he supposes that Iran's "Tudeh Party supports [Ayatollah] Khomeini because he humiliates the United States. And every day of humiliation costs the prestige of the United States. And it is the mightiest Western power. It is a great pity that it is so helpless."

Asked if the United States could station its forces in his country, Begin replied, "Well, I said always to our American friends, we are allies, and if you want facilities in our country, we shall put them at your disposal. I would recommend it to the [israeli] government. I can only speak on my own behalf."

His suggestion about U.S. conventional forces came when interviewer Barbara Walters, inquiring what advice Begin may have as to the 53 Americans held hostage in Iran, pointed out that Israel's policy has been to use force when any of its citizens are taken.

But Begin declined to advise the United States "to use force at the price of the lives of the hostages. I would not give such a advice." If force is used, he said, "maybe the majority of them, perhaps all of them, will be killed."

"We feel so deeply for the American people, for the president, for the families," Begin said. "Perhaps we understand it better than any other nation."

Meanwhile, President Carter's Mideast peace negotiator expressed "hope" that the Palestinians will join the discussions between Egypt and Israel on Palestinian autonomy.

Ambassador Sol Linowitz said his hope was based on movement in the direction of establishing "full autonomy," although he said the phrase has yet to be defined to the satisfaction of the Egyptians, Israelis and Palestinians. Agreement on a mutually acceptable understanding of the phrase has moved closer, he said on "Face the NATION" (CBS, WDMV).

Unless this full autonomy does give the Palestinians the sense that they are going to have a very substantial measure of control over those things that are important in their lives, they won't enter in these talks, they won't become involved in the elections, and therefore they won't become participants," Linowitz said.

If Egypt and Israel "are convinced that progres is being made and more progress can be made," they may extend their discussions of Palestinian autonomy past the May 26 deadline, he said.