Ballet dancer Rudolf Nureyev has been cleared to return to the Soviet Union for the first time since his 1961 defection so he can pay a brief visit to his mother, French officials said yesterday.

Nureyev, 49, now an Austrian citizen and dance director of the Paris Opera Ballet, was granted a 48-hour visa after intervention by French Culture Minister Franc ois Leotard, who has been working on a project for the company to perform in the Soviet Union. The dancer will be accompanied by an official from Leotard's cabinet.

Said Nureyev, who has been trying to visit his native country for several years: "My mother is very old and suffering. I am very moved."

A spokesman for the Paris Ballet would not say when the dancer will depart. Location for Reagan Library

The chairman of the board of trustees of the Ronald Reagan Presidential Foundation, William French Smith, announced yesterday that the board has selected the location for the presidential library and a projected affiliated center for public affairs.

Smith said yesterday the foundation received "well over 30 proposals," most of them extraordinarily attractive. "We had a dilemma of riches, and it was a matter of choosing the best one," he said.

Smith said the trustees have decided upon a 100-acre site in the Thousand Oaks-Simi area of Ventura County, Calif. The site has been offered by Blakeley Swartz, a California partnership, and the foundation has negotiated an option agreement.

The trustees are delighted with the site, which offers views of the surrounding mountains and the Pacific Ocean.

The Ronald Reagan Presidential Foundation is a nonprofit tax-exempt organization created in 1985 to fund and construct the library and center complex. Hahn's Playboy Connection

Former church secretary Jessica Hahn has moved into Hugh Hefner's Playboy mansion after posing topless for the magazine and telling about her sexual encounter with Jim Bakker, according to sources familiar with the Playboy organization.

The San Francisco Chronicle reported the development this week, but Playboy spokesman Bruce Binkow refused to confirm or deny Hahn's presence. "We don't confirm the guest list," Binkow said.

Hahn was reportedly paid $1 million for a 10-page topless photo layout in the magazine's November issue and a lengthy interview that continued in the December issue.

In it, she said she was a 20-year-old virgin in 1980 when, she said, she was seduced by Bakker in a Florida motel room in 1980. She said another evangelist, John Wesley Fletcher, then appeared and forced himself on her.

Fletcher denied having sex with Hahn; Bakker maintained she was the seducer. Reagan Doctor's Soviet Care

Howard House, one of President Reagan's physicians, was hoping to get a look at Soviet hospitals during a visit to the Soviet Union, but got more than he bargained for when heart trouble flared up.

The 79-year-old ear surgeon, who was touring with relatives, his friend, actress Nanette Fabray, and a college alumni group, spent four days in a Leningrad hospital, receiving care and talking with a Soviet cardiologist about medicine in their respective countries.

House, founder of the House Ear Institute in Los Angeles, told the Los Angeles Times Thursday that he took nitroglycerin when he felt chest pains during the August visit, but continued his tour until he felt he was having a heart attack on a Leningrad street. "I'll never complain about American hospital food again," he said. Phil Silvers Look-Alike

A Chinese soldier in Tibet who tried to tear off a British woman's "Sergeant Bilko" T-shirt has become the first known case of someone mistaking the late actor Phil Silvers for the Dalai Lama.

Kris Tate said she was vacationing in Tibet when a soldier on a bicycle noticed her shirt's image of the character Silvers played in the 1950s television series. She said he accosted her and tried to rip off the T-shirt as a crowd of Tibetans gathered, pointing at the shirt and chanting "Dalai Lama!" The Dalai Lama, spiritual leader of the country now under Chinese control, shaves his head. Silvers was bald. As Bilko he has become something of a cult figure in Britain due to BBC reruns of the 30-year-old series.