Hartlepool MP Iain Wright accused Sports Direct of delaying and diversionary tactics during a surprise visit to its HQ.
He was one of a small group of MPs from the Business, Energy and Industrial Strategy Committee who visited the sportswear retailer's Shirebrook HQ yesterday.
And he told the BBC Tees Breakfast Show that while visiting the Derbyshire offices they were recorded by the company.
Mr Wright said: "We turned up with a couple of hours' notice yesterday. We wanted to have a look around and see what progress had been made since June.
"The company weren’t happy to see us, classic delaying and diversionary tactics, I know the warehouse is very very big, but they took us on extraordinary long walks to get to places.
"I wanted to see Unit A, where some of the worst conditions are, and it took us three hours to get there from when we first started.
“At the end we said could we have 10 minutes in a private room just to sum up what we had found and where we go from here, and that’s when Anna (Turley) found the recording device.”
Ms Turley, MP for Redcar, said: “We were in this room and the lady came in with a tray of sandwiches, which was very nice.
"I saw her crouch down and place a small gadget on the floor, then take a moment just to fix it and point it towards us.
"I recognised it as a camera because as we had walked around they had filmed us the whole way, every question we asked, our interaction with the people who worked there.
“I couldn’t believe it, my jaw hit the floor. We just wanted 10 minutes to gather our thoughts and give our feedback. But they were so controlling, so insecure that they couldn’t even allow us 10 minutes to have a conversation by ourselves.
"I couldn’t believe we were being filmed in our own private meeting. We confronted the Head of PR of Sports Direct, who denied all knowledge and said that it [the recording device] could have been there all day.”
Mr Wright said he spoke to Mike Ashley, chairman of Sports Direct, on the phone after the meeting:
“He accused us of planting the recording device ourselves, which I said was ridiculous.
"I said, 'We’re trying to work together to make sure that all workers have decent conditions in the company, but you go around and do this mistrustful suspicious and frankly amateurish thing.'
"I think it says a lot about the values of the company, it’s mistrustful of the workers and it’s mistrustful of outsiders.
I want to work in an open, constructive manner. Some of the allegations we found in our report in the summer were truly appalling and he [Mike Ashley] pledged to try and change things and we want to help him and assist him to do that.
"We have a select committee meeting this morning and we will talk about this. My feeling is that I still want to engage in an open and constructive manner, but the trust is dead.
"Is everything that we are going to do be recorded? Why can’t we just work together to make sure that Mike Ashley’s company has the best conditions for all workers?”