Whistles is looking for investment to open up to 50 international stores over the next five years.
The womenswear chain, which currently has 50 stores in the UK, will bolster its international footprint by opening its first standalone stores outside of the UK.
Whistles chief executive Jane Sheperdson told The Telegraph she would like to double the number of Whistles stores through international expansion, but a stock market flotation is not currently an option.
Whistles currently has concessions in department stores in Paris, Amsterdam, Berlin, Munich, Hamburg, Shanghai and Beijing, as well as two in Moscow and three in Hong Kong.
Another concession is opening in Chengdu, China, with four more planned for Bloomingdales stores in New York, New Jersey and Massachusetts.
In October the retailer revealed it is to launch menswear for autumn 14. The range will be available online and in key stores where it will sit alongside womenswear. It will also be available within selected premium department stores.