Sienna Miller hopes to expand her fashion label to make couture designs.

The British actress - who founded the Twenty8Twelve label with her sister Savannah Miller - has revealed the ambitious siblings want to open a New York store and work on high end dresses because Sienna wants to experiment with luxury fabrics.

Sienna explained: "We'd love to do maybe five couture dresses a year - just to have access to those fabrics. And we'd love to open a store in New York. But frankly, we're really comfortable with where the label's got to now."

However, despite their aspirations, Sienna admitted it is more important to develop strong sales and so revealed they decided not to show their label at London Fashion Week recently, instead arranging private appointments with influential fashion insiders.

She told WWD: "We love doing shows, but because we're not breaking the mold in what we do design wise it's not particularly translating to sales. And the more important thing for us is sales at the moment, especially in this economy."