Japan's Fast Retailing has announced that total sales at its Uniqlo fashion chain fell 7.5% last month.

"September existing store sales dipped year-on-year as the lingering summer heat capped sales of autumn clothing," the company said in a trading update. 

The retail group, which recently lost out in a bidding war for upmarket US chain Barneys New York, is now focusing on expanding its Uniqlo chain internationally, including a flagship store on London's Oxford Street.