Image copyright Anna Turley

The board of Sports Direct has denied knowledge of any attempt to bug MPs from the Business and Skills Committee who were on a surprise visit to the firm's Shirebrook warehouse.

The six MPs claimed an attempt was made to smuggle in a recording device behind a plate of sandwiches to record their private discussions after the visit.

The MPs wanted to check whether Sports Direct had improved employment methods.

The board said it did not authorise the use of any device.

Sports Direct said in a statement: "The board is disappointed that reporting of a possible recording device (the veracity of which has yet to be determined) has overshadowed the truly important issues that the visit should have focused on - the true working conditions and worker satisfaction at Shirebrook."

The firm's founder Mike Ashley said: "I stand firmly behind the people of Sports Direct, who through no fault of their own have been made a political football by MPs and unions."

'Totally bizarre'

The MPs only gave notice on Monday morning that they would visit the Derbyshire site.

After a three hour tour, they gathered in a private room, and were served a series of refreshments, including a plate of sandwiches.

However, Anna Turley, MP for Redcar, said the lady who had served the sandwiches also left a recording device in the room.

"I went over to pick up the device and there it was: a camera and a recording device for the conversation that we were having privately. I'm very disappointed."

Image copyright PA Image caption Mike Ashley founded the company and is under pressure to reform working practices

Ms Turley told the BBC that the situation was "bizarre", and that during the visit the group had been "man-marked" with devices recording everything that was said during the visit.

She said the device in the private room "was on, the red light was showing, it was on, it was recording".

She said the firm had tried to claim it didn't know anything about it - "Mike Ashley's even accused us of planting it ourselves, it was totally bizarre."

Sports Direct, which has around 450 retail outlets, came under fire after BBC and Guardian investigations uncovered working practices at the warehouse which MPs later described as being akin to a Victorian workhouse.

Concern about working conditions led to Sports Direct's founder Mike Ashley being called to give evidence to MPs.

He said at a hearing of the Business and Skills Committee that control of the company may have outgrown him.

But Mr Ashley denied knowing about day-to-day operations at Shirebrook.

Sports Direct has promised to make a number of changes to its working practices.