Speaking to the Irish Independent, the singer claimed that the ITV talent show judge's behaviour is "excruciating" to witness.
She said of the Take That star: "That guy Gary Barlow, he has this horrible way of looking at people. If he was my son I'd be having a serious word with him about the way he's talking to people or treating people. I find it excruciating to look at.
© PA Images
© PA Images
"I don't think the people running the show are the kind of people who think about the effect of their behaviour upon people."
The 44-year-old admitted that she would worry if her teenage daughter auditioned for the show.
O'Connor added: "My daughter wants to be a singer. But I wouldn't want to put her into a situation like The X Factor where she would be vulnerable to being looked at by someone, which is a huge thing for a 15 or 16-year-old to deal with."
> Gary Barlow, Kelly Rowland are terrible judges, say Louis Walsh
> Gary Barlow: 'I regret picking Frankie Cocozza
Watch the video to Sinead O'Connor's defining 1990 hit 'Nothing Compares 2 U':
