Radio station billboards that featured unflattering photos of a bald, scowling Britney Spears have been taken down after the pop star's attorneys threatened legal action.

In a letter to Clear Channel Communications Inc. dated Thursday, Spears' attorneys accused the company of "offensive, unauthorized commercial exploitation" of the 25-year-old singer, and demanded that the three billboards in the Tampa area be removed. The letter was posted on The Smoking Gun Web site.

The billboards, advertisements for WFLZ FM's "The MJ Morning Show," depicted a bald Spears and show host Todd Schnitt along with the slogans "Total Nut Jobs," "Shock Therapy" and "Certifiable."

"We have confirmed that the billboards are down," Clear Channel spokeswoman Michele Clarke said Tuesday. She referred other questions to the Clear Channel offices in Tampa, whose representatives didn't immediately return a call seeking comment.

"Clear Channel has removed the billboards, and I'm not happy with that," Schnitt told the St. Petersburg Times.

A call to the Los Angeles attorney who signed the letter to Clear Channel wasn't immediately returned Tuesday.

Spears completed a month-long stay at a luxury Malibu, Calif., rehabilitation treatment facility in March after attracting an onslaught of media attention for wild behavior that included partying with Paris Hilton and a stop at a San Fernando Valley hair salon, where she shaved her own head.