Her decision to leave the company was announced to senior store staff and area managers on Monday morning on a conference call, the news agency reported, adding that no replacement had been hired yet.

Sports Direct did not immediately respond to a Reuters request for comment.

Mike Ashley, who owns the sportswear retailer, had referred to Byers as the person who "runs Sports Direct", according to the report.

The departure of Byers comes at a time when tough conditions and online sales have forced British retailers such as Debenhams, House of Fraser and Bonmarche to shut stores, go into administration or be taken over.

Her exit could significantly affect the business, but the company would welcome her back if she wanted to return as a consultant, the report said.

(Reporting by Tanishaa Nadkar in Bengaluru; Editing by James Emmanuel)