NASHVILLE, Tenn. (AP) _ Country music star Barbara Mandrell gave birth Friday to her third child, a 7-pound, 7-ounce boy named Nathaniel born in a Caesarean section, officials said.

Miss Mandrell's husband, Ken Dudney, was in the delivery room at the time of birth, said Jeanie Gent, a spokeswoman for the entertainer. The baby will take the middle name Mandrell. A hospital spokeswoman said mother and baby were doing well.

The birth comes one year after the singer suffered a broken leg, two broken bones in her ankle, a badly injured knee and a severe concussion in a traffic accident.

This week, she filed a $10.3 million lawsuit against the estate of the driver of the other car, who was killed in the accident.

Miss Mandrell, 36, is known for such hits as ''I Was Country When Country Wasn't Cool,'' ''Sleeping Single in a Double Bed'' and ''Only a Lonely Heart Knows.''

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ROME (AP) - Norwegian actress Liv Ullmann married an American real estate dealer in an unannounced civil ceremony Friday in Rome's city hall.

Photographers who were at city hall for another event surprised the newlyweds as they came away from the wedding, which was intended to be secret.

Miss Ullmann, 46, and Donald Saunders, 50, both of whom have been married before, were showered with rice by relatives and well-wishers as they stepped out onto the Piazza del Campidoglio, a hilltop square designed by Michelangelo.

Reached by telephone in her hotel room after the wedding, Miss Ullmann declined to answer any questions.

''Since (the city hall wedding) was private, we didn't feel we had to announce it,'' she told The Associated Press.

Miss Ullmann, known for her roles in the films of Swedish directors Ingmar Bergman and Jan Troell, said there would be a religious ceremony on Sunday.

For the civil ceremony the bride wore an orchid in her blond, wavy hair and a light-colored suit with a print blouse, while the groom wore a dark suit with a white shirt.

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LOS ANGELES (AP) - Country-western star Merle Haggard, known for his songs about trains, will take a one-week whistle-stop tour from California to Illinois to promote FarmAid, the concert planned to benefit financially distressed American farmers.

The rail tour will start Sept. 16 in Bakersfield, where Haggard lives, and make 35 stops as it passes through Arizona, New Mexico, Texas, Oklahoma and Missouri before arriving in time for the concert in Champaign, Ill., on Sept. 22.

More than three dozen rock, country and blues stars are expected to perform at the 12-hour concert, which is patterned after Live-Aid, the extravaganza organized by rock musicians to raise money for famine victims in Africa.

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KNOCKANDO, Scotland (AP) - Prime Minister Margaret Thatcher, on a tour of Scotland's distilling region, disclosed Friday that she enjoys an occasional Scotch after work.

But she appeared a bit daunted by the three-liter bottle of the whiskey she received during her visit.

''It's too good to drink,'' she said, holding the huge bottle. ''It is such a rare bottle it will have to go down as an heirloom in our family.''

Mrs. Thatcher said she enjoyed an occasional drop, ''but perhaps not on the scale you would wish, because that would not quite become the office I hold.''

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ATLANTA (AP) - The son of TV magnate Ted Turner starts a new job this week in the Moscow bureau of his father's Cable News Network and says he hopes he won't be treated like the boss's son.

Robert Edward ''Teddy'' Turner IV will work as a researcher, tape editor and cameraman in the network's six-person Moscow bureau.

''I'll be disappointed if they go easy on me,'' said Turner, 22, who spent six hours a day learning Russian to prepare for his assignment.

While his goal is to work in the business end of his father's empire, Turner wants to learn all aspects of the operation - except reporting.

''I'd rather be on the other side of the camera,'' he said. ''I don't think I have the voice or the looks for the on-air stuff.''

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BELGRADE, Yugoslavia (AP) - Jure Franko, the 23-year-old Yugoslav World Cup skier and Olympic silver medalist, is quitting skiing because his hips are ''worn out'' from an incurable ailment, the Politika Ekspres newspaper reported Friday.

''This is the end of Franko's skiing career,'' said Tone Vorgrinc, director of the Yugoslave Alpine Team.

Franko won the silver medal in the giant slalom at the 1984 Winter Olympics in Sarajevo.

Another promising young Yugoslav World Cup skier, 18-year-old Rok Petrovic, is having problems with a ''serious back muscle injury'' and will have to undergo treatment in Austria, the newspaper reported.