Sports Direct’s auditor, Grant Thornton, is being investigated over an alleged undisclosed deal between the retailer and Mike Ashley’s older brother.

The Financial Reporting Council (FRC) said today it has launched a probe into Sports Direct’s accounts after “reports of an arrangement between Sports Direct and Barlin Delivery”.

The delivery broker handles international orders for Sports Direct and is owned by John Ashley, the brother of the retailer’s billionaire founder Mike.

In August it was reported that Barlin Delivery received a share of the revenue from Sports Direct’s website orders that are dispatched overseas.

Sports Direct said at the time that its auditors had concluded that no disclosure was required over the arrangement with Barlin.

An FRC spokeswoman confirmed to Retail Week it is Grant Thornton that is being investigated under its regulatory powers.

Intense scrutiny

Sports Direct has been dogged by controversy this year as it has come under intense scrutiny from MPs, media and unions over its working practices and corporate governance.

In the latest twist, Mike Ashley last week challenged MPs to a live TV debate at its Shirebrook headquarters.

Sports Direct’s share are trading down 2.5% today.

The retailer has yet to respond to a request for comment over the investigation.