At times Lord Sugar was irate as he spoke at the constructive dismissal hearing, at one point saying he wished he has employed another contestant "instead of her" pointing at Stella English.
In response to Ms English's accusation that referring to her, he said: "Nice girl, don't do much", Lord Sugar said:
"Absolute garbage, total garbage...why would I make a statement like that which is tantamount to an insult."
He also dismissed other claims by the 34-year-old as "total nonsense, lies, blunt lies".
Entrepreneur Lord Sugar has accused a former winner of his TV series The Apprentice of being a liar and attempting to blackmail him.
The 2010 Apprentice winner said she was just an "overpaid lackey" in the job she was given by Lord Sugar, an employment tribunal heard.