JJB has been vulnerable to a bid after its profit warning in July

Analysts believe the bid offer could price shares between 260 pence and 270 pence, valuing it at �600m ($1.08bn).

Last year, JJB's chairman, former footballer David Whelan, attempted to take the company private, but pulled out after failing to win support.

A profit warning in July from JJB blamed bad weather for poor sales at its sportwear stores.

As a result, the Wigan-based group said it expected a 20% profits shortfall.

Uphill struggle

David Whelan owns 25% of the company's stock, while major institutional investors include Fidelity Investments, with 9.9%, and Barclays Global Investors with 4%.

Analysts have speculated that a venture capital firm could be behind the approach.

Retail entrepreneur Tom Hunter holds about 8% via his West Coast Capital investment vehicle, but a spokesman for Mr Hunter declined to comment on whether he is a likely contender.

JJB Sports, which has 448 stores across the UK, has faced an uphill struggle in the face of tough competition since 2003.

Annual profits dropped for the first time last year since it floated on the stock market 10 years ago.