Leonard Slatkin, music director of the National Symphony Orchestra, will also become the next chief conductor of the BBC Symphony Orchestra, officials at the Kennedy Center and the BBC announced yesterday.

Slatkin will be the first American to hold the position with the BBC orchestra.

The appointment will not change Slatkin's contract with the NSO, which was extended last April to run through 2003. He is committed to spend at least 16 weeks a year with the NSO.

In an interview yesterday, Slatkin said he had not yet signed a contract with the BBC, and he described his future duties only in approximate terms. His contract should begin in October 2000 and run through 2003. He is slated to conduct five or six programs during the regular BBC season, and four or five more during the summer.

The appointment assures Slatkin, 55, of important bases on both sides of the Atlantic. Conducting the BBC orchestra will give Slatkin a major presence on the all-important London musical scene.

The BBC Symphony Orchestra was founded in 1930 as the flagship performing ensemble of the British Broadcasting Corp., and it gives both public and special-broadcast concerts. It is best known as the resident orchestra for the high-visibility BBC Proms concerts, a summer-long music festival held in London's Royal Albert Hall and broadcast, via radio and television, to millions worldwide. English conductor Andrew Davis, who led the BBC orchestra for the past decade, will officially step down in 2000. Davis will become music director and principal conductor of Chicago's Lyric Opera in September 2000.

Slatkin is a familiar presence in the English musical world. He has been a regular on English podiums since 1984 and has earned a reputation for championing English composers from Elgar and Vaughan Williams to the Washington-based Nicholas Maw.

It's easy to understand why the BBC would find Slatkin an attractive candidate. Along with championing British music, Slatkin has an extremely wide-ranging repertoire, with a special interest in accessible contemporary music. He's also radio friendly: His "Discovering Music" series airs weekly on Radio 3, the BBC's classical music station heard across Britain, and in the United States he's a regular commentator on National Public Radio's "Performance Today."

John Evans, who heads orchestral programming for the BBC, said in a statement yesterday that "the extraordinary range of Leonard's repertoire, his passionate commitment to new and innovative programming and his instinctive flair for communicating with audiences make him an ideal figure for an orchestra committed to the public service ethos through broadcasting."

A spokesman for the BBC said yesterday that general feelers went out for a new conductor a year ago, when Davis announced his departure. Negotiations began in earnest in April although, when asked last month about the possibility of a BBC appointment, Slatkin said he hadn't heard of any such thing.

The Kennedy Center wholeheartedly endorsed the new post for Slatkin, playing down any discussion of whether it will conflict with his duties in Washington.

Kennedy Center Chairman James Johnson said, "We are proud that Leonard Slatkin, a premier American conductor, and the work he is doing with the National Symphony Orchestra here at the Kennedy Center, are being admired internationally."

In the age of jet travel and fax machines, conductors routinely hold down several music directorships concurrently. Indeed, during his 19-year tenure with the St. Louis Symphony--an ensemble he elevated from a respectable provincial status to one of the top American orchestras--Slatkin also held various other directorships. From 1991 until this season he directed the Cleveland Orchestra's summertime Blossom Music Festival. In 1997, Slatkin was given a three-year stint as the principal guest conductor of London's Philharmonia Orchestra. It's impossible to predict if Slatkin's two positions will increase his prestige and thus bring musical riches--top-name guest conductors, soloists and the possibility of recording projects--to both orchestras or simply divide resources that prove to be finite.

CAPTION: Leonard Slatkin conducting the National Symphony Orchestra at the Kennedy Center.

CAPTION: Leonard Slatkin already has a radio show that's broadcast on the BBC.