Morocco reacted cautiously today to a new Organization of African Unity peace plan agreed upon hours earlier aimed at solving the sticky dispute over the Western Sahara that has brought the OAU to the brink of collapse.

The OAU's 19th summit, which was postponed twice last year when delegates were unable to decide whether to seat a delegation from the Polisario, the Western Sahara guerrilla organization, appeared to end on an upbeat note with the approval of today's resolution.

The resolution called for direct talks between Morocco and the Polisario and for a referendum to be arranged within the next six months to allow the Western Sahara's mainly nomadic population to determine who should govern the territory.

Moroccan Foreign Minister Mohammed Boucetta registered his country's reservation of the mention of the Polisario in the document Friday and was noncommittal when asked this morning whether Morocco would agree to meet with the Polisario.

Boucetta did not completely rule out a face-to-face meeting, however. "I do not yet know completely how things are going to turn out," he said, "but given our reservation, I think we can, if there is good will on both sides, proceed toward a referendum."

The territory, about half the size of Texas, is claimed both by Morocco and the Polisario, which has been fighting Moroccan troops since 1975, when Spain handed over the administration of what was then the Spanish Sahara to Morocco and Mauritania. Mauritania later withdrew its claim to the territory.

The Polisario leader Mohammed Abdelaziz told reporters today that the OAU resolution to bring his group to the negotiating table with Morocco was "a victory of reason, right and justice." The resolution is considered an important advance for the Polisario in the front's struggle for recognition as it is the first time it has been officially named in an OAU document.

A highly placed Moroccan official later indicated that Morocco was determined to see the referendum happen but was evasive about talks with the Polisario. Another delegation member was more blunt. "We are not willing to sit down and talk at the same table with these people because we do not recognize them," he said. "How can they just come to Morocco and phone the king Hassan II and say we are going to talk? It's very unclear."

Nevertheless, observers said the new peace proposal appeared to be weighted in Morocco's favor. The referendum was originally agreed upon at the June 1981 summit in Nairobi, Kenya. Several points favorable to Morocco that were agreed upon by an implementation committee of seven countries mostly friendly with Morocco were included in the new resolution.

Morocco has been asked to confine its troops to barracks but not to withdraw its military presence from the Western Sahara. A combined OAU and U.N. peace-keeping force also has been recommended to supervise the referendum.

The Polisario may delay implementation of the peace plan because the referendum is to be conducted within the framework of the existing Moroccan administration. One obstacle the guerrilla organization has raised is the question of just who should be allowed to vote. The OAU has stipulated that only people living in the area and refugees who are in camps in neighboring Algeria and Mauritania can participate. The Polisario claims that there are up to 1.5 million Western Saharans. A December 1982 Moroccan census published last month says the population is 130,000.

The conflict between Morocco and the Polisario gained significance for the rest of Africa when the OAU's outgoing secretary general, Edem Kodjo of Togo, admitted the Polisario's self-proclaimed Sahara Arab Democratic Republic as the organization's 51st member in February 1982 at a meeting of foreign ministers.

The constitutionality of the move has been contested by nearly half of the organization's member states and has threatened to make a mockery of the pan-African body's title, the Organization of African Unity. Two previous attempts to convene the 19th summit in Tripoli, Libya, last year were frustrated because of the Polisario delegation's insistence on being seated. The third attempt in Addis Ababa, the seat of the OAU secretariat, was successful thanks to a last-minute concession by the Polisario, whose representatives announced that they would not attend the meeting.

There are indications that the apparent compromise on the Western Sahara may have been achieved well before the summit in behind-the-scenes negotiations between Morocco and Algeria. Algeria, along with Libya, has backed the Polisario fighters with arms, training and refuge. But there are indications that Algeria may want to speed up a solution because the cost of supporting the movement is proving to be a drain on its finances.

Black African OAU members reportedly were losing patience over the Western Sahara issue, saying that the Arab nations should not bring their squabbles to the OAU.

The Associated Press added:

After apparently weathering the Western Sahara crisis, African leaders were deadlocked over another issue: the election of the OAU's top official.

OAU sources said four ballots failed to produce a majority for any of three candidates for OAU secretary general and that support was growing for Nigeria's Peter Onu, an OAU assistant secretary general for 11 years, as a compromise candidate.

The three other candidates were Foreign Ministers Abdulai Conteh of Sierra Leone, Alioune Blondin Beye of Mali and presidential adviser Paul Okumba of Gabon.

Despite the stalemate over the successor to outgoing Secretary General Kodjo, delegates said they expected the issue to be resolved in time for the OAU to conclude its summit by Sunday.

In addition to dealing with the Western Sahara, the OAU in four days of meetings condemned South Africa's white-minority government and urged it to withdraw from Namibia.

It also condemned Israeli policies in the Middle East, urged creation of a homeland for Palestinians, reviewed the situation in civil war-shattered Chad and adopted a $22 million budget for 1983-84.