An unhappy Simon Cowell has also spoken to the contestants for the first time, according to The Mirror.
Cowell - who is still an executive producer of the show although he no longer sits on the panel - is said to have told the remaining finalists that he has concerns about their "quality and dedication", challenging finalists to "demonstrate [that] you are a recording artist".
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A production source told the paper: "Cowell wasn't messing around when he spoke to them and he left them in no doubt they all needed to improve.
"He can't be here because he is so busy in the States but he hopes this will help the singers and the ratings."
Meanwhile, The Sun reports that Gary Barlow invited the other judges and Xtra Factor hosts Caroline Flack and Olly Murs to dinner at his house on Wednesday evening to discuss the show.
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"Everyone is worried about how well the show is doing and Gary took matters into his own hands by arranging a gathering," a source claimed.
"He told them they need to make sure the show gets stronger as they don't want to be beaten by [Strictly Come Dancing] again."
The insider - who claimed that Kelly Rowland and Tulisa Contostavlos have patched up their previous differences - said that the judges left the meal having promised to "knuckle down with their acts to make X Factor better".
The X Factor next airs this Saturday and Sunday (November 5 and 6) at 8pm on ITV1.