Gwen Stefani is suing a US fashion retail chain claiming designers copied the heart trademarks from her clothing lines.

The fiesty singer claims Forever 21 bosses engaged in "acts of trademark infringement".

Gwen,through her Harajuku Lovers, LLC company, is seeking to stop Forever 21 from modelling clothes based on her own designs, as well as unspecified monetary damages.

Mixing sporty looks and evening wear with a global street perspective, Stefani's contemporary L.A.M.B. line has been a big hit on theNew York fashion week catwalk last year.

L.A.M.B spells out the initials of Love Angel Music Baby which is also the name of Gwen's first solo album.