Japanese casual wear giant and owner of the hit Uniqlo fashion label, Fast Retailing Co Ltd, on Wednesday reported a 24.3 per cent year-on-year plunge in September same-store sales - its 12th consecutive monthly sales fall.

The company said that slide was less steep than the 29.9 per cent fall suffered in August and added it would announce its full-year results on October 17.

Fast has downgraded its profit forecast twice this year but in August said it still plans to open 100 new Uniqlo stores that will take its total number of outlets to 640 by next August.

Earlier this year, the company said its founder and president, Tadashi Yanai, will step down as part of a management reshuffle but remain as chairman. Managing director Genichi Tamatsuka will take up the role of president next month.