April 29 (Bloomberg) -- The Swedish state has demanded ABBA star Bjoern Ulvaeus pay 87 million kronor ($11.84 million) in back taxes, Ulvaeus attorney Sven Rygaard said, confirming reports in Dagens Nyheter and on the British Broadcasting Corp..

The Swedish tax authorities are treating as Ulvaeus' personal income royalties received by a company into which royalties from Ulvaeus' copyrights were paid since the 1970s, Rygaard said. The BBC yesterday cited Swedish tax agency spokesman Jan-Erik Backman as saying Ulvaeus had avoided tax.

``Everything has been done according to all the relevant laws and of course with a view to prudent tax planning,'' Rygaard said in a telephone interview from Stockholm today. ``It's of course difficult to educate the tax authorities in the complicated world of intellectual property law.''

ABBA topped the U.K. music charts nine times between 1974 and 1980 and the 1977 song ``Dancing Queen'' was their only U.S. No. 1, according to the group's Web site. The band's name was an acronym of the initial of the four members' first names. The group, which rose to prominence after winning the Eurovision song contest in 1974, broke up at the end of 1982.

Sweden's tax authorities claim Ulvaeus' creation of a network of companies ``has just been a construction to avoid taxes,'' the BBC quoted Backman as saying.

According to Dagens Nyheter, Sweden also wants ABBA star Anni-Frid Reuss-Lyngstad to pay 12 million kronor in undeclared taxes. Reuss-Lyngstad, who lives in Switzerland, doesn't have to pay personal income tax in Sweden, though income derived from her record company in Panama is taxable in the Nordic country, according to the tax authorities, the newspaper reported.

Hootenays, Chess

Ulvaeus and fellow ABBA star Benny Anderson started writing songs together in 1966, when Ulvaeus was a member of folk music group the Hootenays, according to ABBA's Web site. Anderson was at the time the keyboards player for the Hep Stars, ``Sweden's biggest pop group of the 1960s,'' according to the site.

The two men teamed up in 1970 with Agnetha Faltskog, who married Ulvaeus a year later, and with Anni-Frid Lyngstad.

The group first called themselves ABBA -- also the name of a Swedish canned fish company -- in 1974.

Ulvaeus and Anderson collaborated with Tim Rice, the co- writer of ``Jesus Christ Superstar.'' on the musical ``Chess'' as ABBA faded away in 1982.

To contact the reporter on this story: Tasneem Brogger in Copenhagen at at tbrogger@bloomberg.net