UNESCO nominee: US return essential. Controversial UN agency finally settles on new leader, but US says that's only a start in process of revitalization

After a protracted contest, UNESCO has nominated a new director general. The winner is former Spanish Education Minister Federico Mayor. His nomination by the 50-member executive board, set after a stormy all-night vote this weekend, marked the end of 13 years of leadership by the controversial Amadou Mahtar M'Bow.

Mr. Mayor told reporters that his first priority will be development in Africa. High on his list will also be encouraging the United States and Britain to rejoin the UN Educational, Scientific, and Cultural Organization, a move he considers ``absolutely essential to retore UNESCO's principles of universality.'' The two countries withdrew in 1984 and 1985 alleging an anti-Western bias in the agency and mismanagement of funds.

The US has adopted a wait-and-see approach. ``We see the election of a new director general as a first necessary step in a long process of revitalization that will be needed before the US returns,'' said the US observer to UNESCO, Terry Miller.

One consideration likely to slow an immediate return is the heightened role of the Soviets. ``The US and Britain don't want to end up footing the bill for an organization that is Soviet dominated,'' said a knowledgeable observer.

The US also questions how useful UNESCO really is. ``We haven't really seen a constituency in the US that seemed concerned about UNESCO,'' Mr. Miller says. ``People who might have defended UNESCO before are too busy trying to defend the United Nations in New York. A return would mean obtaining an allocation of $40 million a year from a tight-fisted Congress. To do that UNESCO would have to show that it was worth more than other competing international organizations.''

African states had fought hard for the reelection of Mr. M'Bow, who, as a Senegalese, was the first African to hold a top UN post. He consistently tried to direct the organization with the perspective of someone coming from the third world. He argued strongly that third world citizens were receiving a distorted image of themselves because most of what they read came from predominantly Western-controlled news media.

M'Bow also argued that entire peoples as well as individuals had the right to freedom, and that what might seem like free enterprise in industrialized countries might seem like egotism and personal greed in an underdeveloped country. M'Bow's views on the impact of media on the third world led him to back a series of programs called the New World Information Order. Western countries rejected the proposals on the grounds that they provided a pretext for increasing censorship.

While M'Bow had been criticized for running UNESCO as a personal fiefdom, US diplomats made it clear that it was ideological factors that led the US to withdraw. The departure of the US, Britain, and Singapore cost UNESCO one-third of its budget.

Faced by rising opposition, M'Bow said a year ago that he would not seek a third term. But by last spring he was campaigning. By last summer he had the support of the Organization of African Unity and its chairman, Zambian President Kenneth Kaunda. For a while it looked as if M'Bow might win the nomination. The candidate who seemed to have the most Western backing, Pakistani Foreign Minister Shahabzada Yaqub Khan, pulled out when it became clear that he couldn't win.

The deciding factor proved to be the Soviets, who control six votes on the board and were determined to see M'Bow step down as part of a general effort to revitalize UN organizations. On Friday, Soviet delegate Yuri Khilchevsky went to M'Bow and told him that it was all over. M'Bow said he would withdraw if given 24 hours as a grace period.

Mayor's nomination goes before the agency's general conference Nov. 7.