Simon Cowell is said to be "very, very disappointed" after the names of the X Factor finalists were leaked on the internet.
The 12 names through to the live shows were posted on a website, just days before the finalists are revealed on the ITV1 programme.
"Simon is very, very disappointed," an unnamed source told the Daily Mirror.
Simon, the show's creator and one of the judges, keeps the finalists' names under lock and key. Journalists are banned from the room when the decisions are made and the acts are made to sign confidentiality agreements.
The upcoming two episodes will see the remaining 36 acts from the boys, girls, over-28s and groups categories whittled down to the final 12.
A spokesperson for The X Factor has declined to comment.