Things turned personal between the judges on The X Factor live shows when Gary Barlow accused Tulisa Contostavlos of having "fag ash breath".
The comments came after Christopher Maloney's performance when Contostavlos criticised Barlow for the song he had chosen for his act.
She said: "You do the same thing over and over again with him and it's not working."
Barlow replied: "Tulisa, I don't know what's offended me more, - what you said or the fag ash breath." His comments can be heard in the video below at 4.33 minutes.
Moments later Contostavlos interrupted host Dermot O'Leary and said: "Just a note for Gary - lay off the red wine because I can really smell that as well."
A show source later said the pair were locked in "peace talks" in a dressing room after the show.
They were locked in a dressing room for peace talks after the show; just the two of them. Gary apologised a lot. Tulisa was angry but eventually she accepted his apology. Gary feels really, really bad about what he said. It was speaking without thinking in the spur of the moment and he didn't mean it.
Later on ITV2's The Xtra Factor Barlow was asked if he had been drinking red wine and he said he had "a little sip" in his dressing room and went on to apologise to his fellow judge.
He said: "Can I apologise to Tulisa - I mean it. You have the freedom to be as personal as you like to me for the rest of the series - insult me."
Contostavlos told The Xtra Factor that Barlow had once said he "loved" the smell of cigarettes because it reminded him of the days he used to smoke and Barlow agreed.
When asked if she was "all right" with Barlow, Contostavlos replied: "Yeah we're good, yeah, course."
Earlier in live shows Robbie Williams confirmed he is a fan of controversial X Factor hopeful Rylan Clark despite Take That bandmate Barlow criticising the 24-year-old's performance each week.
Williams first revealed his support for Clark during last week's live shows in a tweet which read: "TEAM RYLAN ALL THE WAY VOTE RYLAN".
Responding to the tweet backstage, Barlow said to Clark: "I don't think he (Williams) does his own tweets, don't get too carried away."
On tonight's Halloween special, Williams was shown giving advice to each act ahead of the fourth live round of the competition.
Williams and Clark were quick to hug backstage and, after helping Clark with his vocals, Williams said: "Gaz, I don't understand how you're missing the obvious brilliant talent of Rylan, but I'm not, I am strictly team Rylan all the way."
Clark, who is mentored by Nicole Scherzinger, celebrated his 24th birthday on Wednesday by throwing a Halloween-themed party in central London and he invited his fellow contestants, judges and other celebrities.
On Saturday he performed songs from three different artists including Britney Spears and Scherzinger.
Speaking after Clark's performance, Barlow said: "It's hard to imagine I ever fell out with Robbie Williams isn't it?"
He said: "The music was so loud I couldn't hear you singing - that's a good thing."
In response to the feedback, Rylan said: "Gary, I really do want to impress you and I mean that and if I get through next week I promise you there is going to be none of this, I'm going to stand here and sing you a song."
Gary replied: "You're on."
Mentor Scherzinger said Clark did a "beautiful job" and, turning to Barlow, she said "it's all about team Robbie Williams", which raised a cheer from the crowd.
Judge Louis Walsh said: "I'm with Robbie Williams totally because Robbie gets the whole entertainment factor, that was amazing."
Contostavlos said Clark's performance felt "like Wednesday night at Mahiki all over again".
Look, do you know what, at the end of the day, no matter what anyone says, you may not have the strongest voice in the competition but every time you step on that stage you deliver to the best of your ability.
Sixteen-year-old Ella Henderson performed Evanescence's Wake Me Up, which received mixed reviews from the judges.
Barlow and Scherzinger said they were not impressed with the song choice, Walsh criticised Henderson's hair and mentor Contostavlos said "you always make songs your own and that is what makes you so special".
Earlier today talent show bosses said contestant Lucy Spraggan would not be able to perform tonight due to illness and would automatically go through to next week's show.
One of the remaining 10 acts will be voted off in tonight's show on ITV1 at 8pm.