A photo caption yesterday identified Zaki Aslan incorrectly. He is a senior diplomatic interpreter for the State Department, not for Saudi Arabia's King Fahd.

Saudi Arabia's King Fahd asked President Reagan yesterday to take the lead in hammering out an Arab-Israeli agreement based on "the just cause of the Palestinian people," but Reagan said "direct negotiations" between Arabs and Jews is the way to Mideast peace.

The Saudi monarch is the first top Mideast visitor at the White House in Reagan's second term. His talks with Reagan are a first step toward renewed U.S. activity to promote a Middle East peace process. Though the atmosphere of the talks was described as unusually relaxed, the positions made public by Fahd, Reagan and Secretary of State George P. Shultz suggested that there are large gaps between the Saudi and U.S. positions.

"The Palestinian question is the single problem that is of paramount concern to the whole Arab nation . . . . It is the one problem that is the root cause of instability and turmoil in the region," Fahd said in an arrival speech that set the stage for his discussions.

"I hope, Mr. President, that your administration will support the just cause of the Palestinian people," he added.

Reagan, in his welcoming remarks, said "the security of Israel and other nations in the region and the legitimate rights of the Palestinian people can and should be addressed in direct negotiations."

Shultz, in remarks at a State Department luncheon in Fahd's honor, went further, declaring that "there is only one road" to Mideast peace: "direct negotiations between Israel and its Arab neighbors based on the territory-for-peace formula of U.N. Security Council resolution 242."

The private discussions between the Saudi king and his U.S. hosts were enlivened by a report from Jordan's official news agency that King Hussein and Palestine Liberation Organization chairman Yasser Arafat have reached agreement on "a framework for common action" to deal with the Palestinian problem.

State Department officials said neither they nor the visiting Saudis were certain what the announcement means, but the U.S. sources expressed skepticism that a solution has been found to the longstanding disagreement over the desirability of and terms for Arab negotiations with Israel.

"It seems most unlikely that the discussions between Hussein and the PLO will end at this point," a State Department official said.

Another administration official, while saying that no authoritative reports have been received from Jordan, said indications are "we're still months away" from agreement on an Arab position on talks with Israel.

Fahd, in remarks at the State Department luncheon, which followed his meeting with Reagan and other officials, spoke of areas of disagreement between the U.S. and Saudi sides but said talks between friends should be "built on frankness and reality."

It should not be forgotten, Fahd said, that the Soviet Union is watching and waiting for opportunities in the troubled Middle East. He indicated that this should be an added incentive to the United States to use its influence for peace.

In his arrival speech on the White House South Lawn, Fahd put the blame on Israel for the plight of the Palestinians. He said that while most other Arab nations gained freedom and independence, "the Palestinians, who were never aggressors or invaders, found themselves, through no fault of their own, the victims of unjust aggression."

These remarks, which U.S. officials said were repeated in substance in private conversations, suggested that the U.S.-Saudi dialogue has remained startlingly unchanged in some respects since the meeting 40 years ago this week of King Abdul Aziz, Fadh's father and the founder of Saudi Arabia, and President Franklin D. Roosevelt.

Reagan and Fahd alluded in the welcoming ceremony to the meeting, which took place Feb. 14, 1945, aboard a U.S. warship in the Middle East as Roosevelt was returning from the Yalta conference. According to the memorandum of the meeting, signed by Abdul Aziz and Roosevelt, the Saudi monarch complained bitterly about Jewish immigration to the Holy Land and of displacement of the Palestinians. Roosevelt replied that he would make no move hostile to the Arab people.

A senior administration official who briefed reporters at the White House following yesterday's discussions said a new U.S. arms sale to Saudi Arabia was not discussed.

Reagan hinted at the case he is expected to make to Congress later this year for the sale of 40 additional F15 jets to the Saudis.

The president noted that the war between Iran and Iraq "is raging only a few minutes by air from Saudi territory."

He added that the United States will do what it can through diplomacy to end the fighting and that "we will cooperate with Saudi Arabia to ensure the integrity of your borders."

On the same theme, Shultz spoke at the State Department luncheon of the "years of effective military cooperation" between the United States and Saudi Arabia, which he said created a Saudi "shield" against the threats from Iran.

"The kingdom's capacity to defend itself when challenged is proof of the wisdom of that cooperation," Shultz said in an apparent reference to the Saudi air force's downing of Iranian jets in the Persian Gulf last June.

The full-dress White House welcome for Fahd, including a large honor guard and a 21-gun salute, occurred in bright sunshine and warmer temperatures than the capital has seen in most recent days. Fahd drew laughter and applause at the end of his speech by saying, "I would like to thank God for giving us a beautiful sunny day today."

Fadh, wearing traditional Arab headdress and robes, spoke a few sentences of English at the beginning and end of his remarks and apologized for speaking primarily in Arabic. Reagan, who was hatless and wearing an overcoat, began his remarks with a Arabic phrase that is a warm and well-established greeting used among friends.