Sony Music Entertainment filed a breach-of-contract suit against country group Dixie Chicks [ tickets ] on Tuesday (7/17), asking the court to uphold the group's current contract and to bar it from signing with another label.

The filing of the complaint follows a dispute over royalties from the two albums that Dixie Chicks have released on Sony since 1997. In it, Sony alleges that Dixie Chicks' contract calls for five more albums, and calls the group’s claims that they’ve been underpaid a "sham."

On Wednesday (7/18), Sony issued a statement regarding the suit: "We filed this complaint to confirm that the Dixie Chicks remain signed to an exclusive recording contract with Sony Music. We take great pride in the work we’ve done in establishing the Dixie Chicks as the most popular and biggest selling female Country group of all time. We have tremendous respect for all of the Dixie Chicks, as well as for their extraordinary music."

Dixie Chicks' two albums on Sony, "Fly" and "Wide Open Spaces," have sold more than 19 million copies.

Representatives for Dixie Chicks declined comment on the suit.

Entertainment attorney Jim Zumwalt was quoted in the Nashville Tennessean as saying that Sony's suit is "extraordinary" for this kind of dispute, and that this nature of disagreement is generally settled behind closed doors.

A similar dispute cropped up in early 1999, after the success of "Wide Open Spaces." At that time, Sony agreed to renegotiate Dixie Chicks' contract, and the parties reportedly agreed to expand the number of albums in the deal from six to seven. According to published reports, Dixie Chicks requested another renegotiation last summer, but Sony declined.

In an interview on "60 Minutes II" last fall, after Dan Rather suggested that Dixie Chicks have generated up to $200 million in sales. Band member Emily Robison reportedly responded by saying, "You’re depressing me because we see so little of that."