Spears has recently performed in several LA nightclubs

The WFLZ billboards included the slogans "Total nut jobs", "Shock Therapy" and "Certifiable", which ran across pictures of a bald Spears.

Law firm Lavely and Singer demanded the "immediate removal" of the banners in a letter to the station.

WFLZ's Todd Schnitt said the adverts were down but he was "not happy".

In February the star, who shot to fame with her debut single Baby One More Time in 1998, was photographed shaving her own head in a Californian hair salon.

She has been seen in various different wigs

Spears's legal team claim the company which owns the station, Clear Communications, was "already exposed to substantial liability for its offensive, unauthorised commercial exploitation" of the star's photograph.

Spears is trying to stage a comeback and is reportedly working on a fifth album.

In recent weeks she has performed a series of short concerts in nightclubs around Los Angeles.

Last month the singer admitted she hit "rock bottom" when entering rehab earlier this year, after the breakdown of her marriage, to Kevin Federline, and a spree of high-profile partying.