Angry Russell Brand accused Graham Norton of making his mum cry after the chat show host asked him about his divorce.
In an angry rant (cut from the programme) Brand, 37, also told the presenter he had stabbed him in the back.
Graham decided he had to bring up the split after interviewing, US singer Katy Perry, 27, on his show last week.
He told Russell he had been “very dignified” about the break-up.
But the comedian and movie actor, whose mum Barbara, 65, was in the front row, immediately turned on Graham.
He told him: “My mum is here, I was checking to see if my mum was all right.
“She got upset when you dragged up my marriage. I saw her cry, Graham.
“That’s why I was a little bit embarrassed when I saw my mum crying. You made my mum cry.
“I don’t see you as that sort of person, Graham.”
The mortified host said: “I don’t see myself as that kind of person.” Russell replied: “And yet you are.”
Russell, promoting his film Rock of Ages, told fellow guests, actress Emily Blunt and singer Paloma Faith: “He upped the stakes and stabbed me in the back.”
Graham apologised, saying: “Well I am sorry. That should not have happened. I am genuinely sorry.”
At the end of the show, Graham got down on his knees and apologised again.
An insider said: “The whole thing was really awkward. Russell was furious.”
by Lorelle Heath