The controversy over Sir Bradley Wiggins’ use of corticosteroid injections has hampered Team Sky’s attempts to defend their clean image, according to co-star Chris Froome.

In a month when Sir Dave Brailsford will face a parliamentary select committee to testify as to what he knew about these treatments, Froome has said that he still has unanswered questions about the whole affair.

“People ask me, ‘Do I think it’s tarnished his image?’ I certainly think it’s raised a few questions, that’s for sure,” Froome told the Times.

“A lot of people have said it’s taken the shine off his performances back in 2012.”

UK Anti-Doping is currently investigating a mysterious package transported to France in 2011 where Wiggins was racing.

“I am completely in the dark on that,” Froome said. “I have asked the question. Hopefully we will find out at the end of the investigation.

“Those are questions for Brad to answer about what happened back then. In terms of who did what at the time, I still don’t know all the answers myself.

“I can only deal with what I do know. From what I have seen for myself [at Sky], it’s been completely above board. It’s been clean. I’ve laid all my cards on the table. Everything has been out there for a while in terms of my TUEs.

“We have worked really hard to try to show we are being as transparent as possible. I feel we have made a lot of headway this year, especially on the roads of the Tour. I felt a genuine change in mentality of the French fans, a much warmer reception than it has been in the past.”

“Obviously the team has been through a tough period,” Froome added. “But I would like to think the team has moved on from there and is in a completely different place.

“Looking around the group, riders and staff, I’m surrounded by such a great group of guys who want to work hard and do things the right way. It’s really unfortunate. I don’t think it’s fair that this casts a shadow on that and the work that everyone is doing now.

“There’s still a lot we don’t know. Until those questions are answered, how can we say what actually happened?”

It’s not the first time Froome has admitted his concerns. Back in October, we reported how, speaking to Cycling News, Froome said he was surprised when news emerged of Wiggins’ TUEs as it was the first he’d heard of them.

He said: “Without knowing the exact details of his medical condition, it’s impossible to say if he was operating in a grey area. I had seen Bradley Wiggins using his inhalers so I knew he had asthma, but I wasn’t aware of his allergies.”

Speaking to The Telegraph, Mark Cavendish said: “Maybe Brad needed a TUE legitimately; maybe he could have used something else. But unless you know, it is just speculation. And I’m not going to speculate.

The sprinter drew a parallel with perceptions of his collision with Korean Park Sang-hoon during the Omnium points race at the Olympics.

“You can crop a picture any way you want,” he said. “Even I look at it and go ‘fuck’. Anybody can speculate that it was malicious. You can twist it to how you want. But unless you know, unless you are that person, it is just speculation.”

Froome was granted a TUE to use prednisolone – a drug used to treat various inflammatory and autoimmune conditions – at the 2013 Criterium du Dauphiné and the 2014 Tour de Romandie. Asked the difference between his use of TUEs and Wiggins’ applications, Froome said that he didn’t believe there were alternative treatments for his condition.

“In 2014, I had an asthma exacerbation following the prologue at the Tour de Romandie. I had serious trouble breathing, which was visible to everyone, including journalists who tried to interview me after the stage.

“The team applied for an emergency TUE for a short course of prednisolone. This is the standard treatment for post-infection inflammation in asthmatics that cannot be controlled by standard inhalers. I don’t believe that there are any alternative treatments, and performance enhancement is negligible.”