The German driver sustained a compression fracture of a neck vertebra in an accident during January's Race of Champions in Miami, and missed the first test of the pre-season, citing a "back issue" as the reason for his absence.

Wehrlein travelled to the season-opening Australian Grand Prix, but withdrew from the event after Friday practice. He also skipped the Chinese GP before making his return to racing in Bahrain last weekend.

On Monday the Sauber driver tweeted the first images of himself during his recovery, revealing the severity of his state at the time.

Although his decision to miss the first two races of the season led to criticism in certain quarters, Wehrlein said he simply did not want to share the images earlier.

"I was allowed to, but I didn't want to," Wehrlein said of sharing the photos. "I think I'm not someone who likes to share everything in public.

"My social media I use it more as a race driver where I do my job and then I like to have a private life as well, so I don't share a lot of my private life on social media. And this injury was something private. In the end it was something serious."

Although the full extent of his injury was not disclosed initially, Wehrlein insists Sauber did not hide anything and blamed people for creating "their own fantasy".

When asked by Motorsport.com if he thought the secrecy had been a mistake, he said: "No, I don't think so. As I said already last week, people were judging what I was doing without knowing what my situation was.

"Everyone knew that I was injured. Everyone knew that I had to get the green light from the doctors, I had to be cleared by the FIA, so normally that doesn't happen if you have muscle pain.

"We said it's a back injury and it will be fine with some time. That's what we said. We didn't lie to anyone, we didn't hide anything. We always said I had a back injury. It's not a problem because we knew I would come back soon.

"That's what we said. Then people started to create their own fantasy."

Wehrlein revealed that he already had doubts about his fitness when travelling to the first race of the season, and admitted missing the opening grands prix was mentally very tough.

"I knew what injury I had and how bad it was," he said. "The team knew. Sauber and Mercedes knew what I had and I was never getting pressure from Sauber or from Mercedes because this injury is quite serious and it could have ended my career.

"I drove the car in Melbourne and after the first day I realised it was too early for the back, too early for my fitness. Of course it was very frustrating for me.

"It was a hard time for me. I always knew in my mind going to Melbourne that it could be that I'm not able to race. And then realising on Friday evening it's hard.

"So that was hard, but again, Mercedes and Sauber they haven't pushed me into anything. The support I got from both teams was amazing.

"From Melbourne to here it was a tough time. Also mentally, because there was nothing else in my mind than wanting to come back as soon as possible."

Additional reporting by Jonathan Noble