The trio, who had been selected for the Final 24 judges' houses round, were axed after producers discovered that one of the girls was under the show's age limit of 16.
Mentor Louis Walsh informs Christina, Rachel and Ivette of the news on next Saturday's show.
"They're devastated. Louis has the agonising task of telling the girls they can't continue this year but he softens the blow by suggesting they can try again next year when they are old enough," a show source told The Mirror.
Harmony Hood replace the girls at Walsh's house in Italy's Lake Como. The other groups competing for a spot in the Final 12 are Miss Frank, Kandy Rain, Project A, De-Tour and brothers John and Edward.
The X Factor continues next Saturday at 8pm on ITV1.