The State Department yesterday defended the visit here of a Palestine Liberation Organization official as a gesture toward free expression of ideas, but conceded that he could be expelled if he seeks to publicize his views.

That situation arose when reporters asked the department spokesman, Hodding Carter, why Shafik Al Hout, director of the PLO's Beirut office, had been warned that his U.S. visa could be revoked if his statements at a breakfast yesterday were attributed to him in the press.

Carter was asked how that squares with Secretary of State Cyrus R. Vance's assertion before the Senate Foreign Relations Committee Wednesday that Al Hout was granted the visa "in line with the U.S. commitment to the free exchange of information and ideas."

Despite Carter's contention that there are no contradictions between Vance's statement and the restraints on Al Hout, the spokesman's lengthy exchange with reporters seemed to make only one thing clear - the validity of prediction by department officials last week that Al Hout's visit would be very controversial.

Under U.S. law, PLO officials generally are barred from the United States because of the organization's identification with terrorist activities. When it became known that Al Hout was seeking a visa, there were protests from the government of Israel and from American-Jewish organizations and pro-Israeli members of Congress.

Underlying these objections is wide-spread suspicion in pro-Israeli circles that the Carter administration, looking ahead to the next stage of Middle East peace iniiatives, wants to bring the PLO into the negotiating process and that the Al Hout visit in an opening wedge in this campaign.

That was denied by Vance in his Senate testimony Wednesday. He said the administration has not changed its policy of refusing to negotiate with the PLO until it recognizes Israel's right to exist and accepts United Nations resolutions to that effect.

However, when Al Hout was invited to speak before private groups at several American universities and the Chicago Council on Foreign Relations, State recommended to the Immigration and Naturalization Service that he be given a visa. That was done under a legal provision allowing a waiver for otherwise inadmissible persons if their visit furthers the free exchange of ideas.

But despite the assertion of a State Department official yesterday that "we've elbowed out an opening for the free exchange of ideas," events since Al Hout's arrival here have raised questions about how free and how wide the exchange is likely to be.

On Wednesday, Al Hout met with members and invited guests of the Institute for Policy Studies, a private Washington research group. But those attending were told that the session had to be off the record, with no public repetition, directly or indirectly, of anything he said.

That prompted an editorial in yesterday's editions of The Washington Post calling the restrictions an infringement of basic American liberties. The editorial said it was "shameful" that Al Hout's listeners "must enter into a conspiracy of silence to gain the privilege of talking with him."

Yesterday, Al Hout talked with selected reporters at a breakfast arranged by Foreign Policy magazine. On that occasion, according to reliable sources, lengthy negotiations between sponsors of the breakfast and the State Department resulted in a slight relaxing of the rules: attending reporters were allowed to write about what Al Hout said but could not identify him by name.

When reporters protested to Carter, the spokesman replied that Al Hout's visa restricts him to participation in meetings with the academic group that originally had invited him. Although Carter said Al Hout's visa could be revoked if his actions or statements in the United States contradict the requirements of the waiver under which it was granted, he refused to describe these restrictions.

Several reporters asked whether Al Hout's visa would be jeopardized if his scheduled speeches before academic audiences are reported in the press. Others asked if he will be required to preface each of these speeches with a plea that he not be quoted by name.

In reply, Carter said only that "the penalties of what might happen depend on the circumstances." Al Hout, the spokesman added, agreed to the restrictions when he accepted the visa and "he knows what the requirements are."

In addition, Carter said, any determination that Al Hout has violated the terms of the visa would be made by immigration officials rather than State. However, it is known that most of the organizations sponsoring his visit have been dealing directly with State to determine what he can or can't do.

Meanwhile, there were signs yeesterday that the department may encounter a fresh storm of criticism soon from those who opposed Al Hout's visa in the first place.

In his Senate testimony, Vance said one of the reasons for granting the visa was Al Hout's reputation as a PLO moderate who opposes terrorism. According to persons present at yesterday's breakfast, when Al Hout was asked his views on terrorism, he replied in part: "We have condemned hijacking. But I haven't condemned the armed struggle."

Asked whether State considers that statement a rejection of terrorism, Carter refused to reply on the grounds that he didn't know the identity of the speaker and that it was unrelated to specific acts. Other department sources privately described the answer as "not particularly helpful" if the PLO wants to project an image of moderation.

The thrust of Al Hout's other comments at the breakfast was that the PLO cannot consider joining the U.S. backed Middle East peace talks unless Washington publicly supports a Palestinian state free of any Israeli controls. Although he asserted the PLO is willing to accept the realities of the Middle East situation, his remarks contained no specific sign that the PLO recognizes Israel's legitimacy.