Saudi Crown Prince Fahd called on the Reagan administration yesterday to follow up its victory on the sale of radar planes to Saudi Arabia by starting "the bigger and more important battle it must wage" to bring peace to the Middle East on the terms contained in an eight-point Saudi plan.

Fahd's call for U.S. support for the plan came as Prime Minister Menachem Begin renewed his condemnation of it in a speech before the Israeli parliament and said he would attempt to assemble a bipartisan parliamentary delegation to come to the United States to apply pressure on the Reagan administration to reject the plan.

Begin said leaders of the ruling Likud coalition and the opposition would meet this week to determine the makeup of the parliamentary delegation, which is expected to join the government's "information offensive," focusing its efforts on the U.S. Congress, the White House and public opinion through the U.S. news media, Washington Post correspondent William Claiborne reported from Jerusalem.

Fahd, who is the number two official and day-to-day leader of Saudi Arabia, said his plan represented a "rational and balanced alternative" and one that "differs categorically" from the Camp David agreements, the foundation of the present Middle East peace efforts, which he said were at a "dead end."

The Saudi plan, which was first proposed in August, differs from the Camp David accords primarily in its demand for Israeli withdrawal from all occupied territories and creation of a Palestinian homeland in the West Bank and Gaza Strip with Jerusalem as its capital. Fahd also stressed that there should be "no Palestinian state without the Palestine Liberation Organization."

Fahd's lengthy statement, published by the official Saudi Press Agency yesterday, was seen as a Saudi move to establish a major role in the Middle East peace efforts as the tempo of activity increases with reawakened U.S., Soviet and European interest. Fahd also cited the death of Egyptian president Anwar Sadat and Begin's reelection by a "flimsy majority" as factors making a restatement of the Saudi position timely.

Both President Reagan and Secretary of State Alexander M. Haig Jr. spoke warmly of the Saudi initiative last week. Fahd said he saw Reagan's statement as "a new sign that I hope will be followed by further encouraging signs."

Yesterday, however, after a weekend of hearing harsh Israeli condemnation of the plan in a letter from Begin to Reagan and in a visit from Israeli Ambassador Ephraim Evron, the Reagan administration pulled back from its previous remarks and strongly reaffirmed its commitment to the Camp David accords.

Fahd's discussion of the plan came as British Foreign Secretary Lord Carrington, representing the 10-nation European Community, prepared to begin a mission to Saudi Arabia today to determine whether Western Europe can play a joint role with the Saudis in working toward a Middle East solution.

Carrington, in an interview with Arab journalists in London, called the Saudi proposal "a very important statement." A British official told Reuter that Carrington and the Saudis "will be exploring the common ground" between Fahd's plan and one proposed by the European Community in June 1980.

Fahd said Saudi Arabia and five Persian Gulf neighbors will put the Saudi plan before Arab leaders at a summit conference in Fez, Morocco, on Nov. 25 in an effort to restore Arab solidarity with a broad-based endorsement.

In addition to U.S. support, he also urged renewed Soviet involvement in the Middle East peace process.

As one of the two superpowers, he said, the Soviet Union does not have "a less responsible role" than the United States "concerning events in our region."

The Fahd plan calls for Israeli withdrawal from all territories seized in the 1967 war and removal of all settlements from those territories; guarantees of freedom of worship in Jerusalem; recognition of the right of Palestinian refugees to repatriation and compensation for those who do not wish to return; temporary U.N. trusteeship over the West Bank and Gaza Strip; establishment of an independent Palestinian state with Arab Jerusalem as its capital; guarantees of the right of all countries in the area to live in peace and guarantees of the agreement by the United Nations or key members.

While the original eight points did not mention a PLO role, an accompanying list of conditions essential to their implementation included an acceptance by all sides that PLO Chairman Yasser Arafat is the spokesman of the Palestinian people.

Possibly because of this elliptical reference to its role, the PLO has been lukewarm in its support of the Saudi plan, although Arafat has endorsed it.

Yesterday Fahd said the plan has not mentioned the PLO because it did not seem necessary. "I have not heard about any Palestinians, inside or outside the occupied territory, who want an alternative to the PLO as their sole legitimate representative," he said.

"I cannot imagine that a Palestinian state could be set up without the approval of the PLO's leadership. Hence, no peace without the Palestinian people and no Palestinian state without the Palestine Liberation Organization."

He again called on the United States to recognize the PLO, a step taken by the Soviet Union last month.

Fahd said the Saudi plan had been drawn up as an alternative to the Camp David agreements, which had been rejected by all Arab states except Egypt, "so that the Arab rejection would not be purely rejection and so that we would not leave the field free for Israel to claim that the Arabs have rejected Camp David because they do not want peace."

While he said the eight-point plan had been drawn up by Saudi Arabia alone, he described it as "inspired" by resolutions of Arab summit meetings, especially one in Baghdad that rejected the Camp David accords, and said most of its provisions were based on U.N. resolutions or the U.N. Charter.

While the plan does not "provide a panacea for all ills," he said, it is "nevertheless a modest attempt toward that end" and Saudi Arabia wanted to "place it at the disposal of the Arab nation to hold consultations and exchanges of views and reach conclusions."

In Jerusalem, Begin said the Saudi eight points "cannot serve as any basis for any discussion whatsoever" and "are rejected from start to finish."

Begin combined his rejection of the Saudi plan with a sharp attack on the country itself, saying: "The petrodollar desert kingdom -- where the darkness of the Middle Ages reigns, with the cutting off of hands and heads, with a corruption that cries out to high heaven -- speaks about arrogance of Israel when it dares to try to dictate to us, the ancient Jewish people, what our borders should be, when it seeks to steal away our capital of Jerusalem."