Last week it was revealed that Littner, 72, wouldn't be returning to act as an aide in the next series of The Apprentice due to the severity of his injuries.
Lord Sugar, 74, appeared on ITV's Lorraine on Tuesday where he remarked that he had "lost count" of the number of operations his colleague has had and that he has "gone through a terrible experience".
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“The irony of it is that he was simply going out for a ride on his bike, not racing, not going fast or anything like that," he explained. "Just doing eight or nine miles an hour and came off.”
Lord Sugar added that it was a “horrific accident and he was so upset that he couldn’t join this series”.
He shared that Littner is recovering and later this week will have a six-hour operation which will “hopefully” be his last. Lord Sugar said the pair talk “every couple of days”.
Littner previously shared that his leg was seriously injured in the accident and doctors initially believed they may've had to amputate.
He is being replaced in the next series, which is due to air in early 2022, by the show's first winner Tim Campbell. Baroness Karren Brady will be back in the boardroom alongside Lord Sugar too.
Littner expressed a desire to return to the show as soon as he is able.
With additional reporting by PA.
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