Sharon Osbourne thinks Rita Ora and Nick Grimshaw were unfit to be 'X Factor' judges.

Sharon Osbourne

Sharon Osbourne

The 63-year-old star is returning to the talent show this year and has taken aim at two of the judges from 2015, arguing they did not have what it takes to be a success on the programme.

She said: "If I was a contestant and there was a young girl or guy on the panel, who's had success but not long success because they are so young, and they were telling me what I should and shouldn't do, I would tell them what to do.

"I would. I think when you are advising people on their career, it always comes better from people who have had experience through age and who have had a long career themselves.

"If somebody has just happened, and they are two years into their career, then they can't tell someone what to do, or what they feel they should do.

"Or they can tell them, but the person they're telling is going to be like: 'Who are you? Are you going to be here in five years?' They haven't passed the test of time yet."

Sharon will feature alongside Simon Cowell, Nicole Scherzinger and Louis Walsh on the programme this year, and she explained how the current incumbents differ from the previous judging panel.

She told The Sun on Sunday: "Everyone has a test of time to see whether they are in or they are out. You get so many instant hits but three years down the line, they are gone.

"But we - Simon, Nicole, Louis and I - have all got decades in the business."