La Reid thinks Mariah Carey is too old to make a hit record.

The 45-year-old singer's ability has been doubted by the Sony label boss as he believes it's ''not realistic'' for her to have another chart-topping single, despite the fact she holds the record for the most US number one singles for a solo artist.

He said: ''Mariah Carey made her first hit record in 1991.

''To even be on the radio at this point in her career is a huge accomplishment, because radio doesn't cater to veteran artists or legends.''

The former 'The X Factor US' judge continued to say other ''veteran'' artists had not succeeded in creating hit singles later in their careers, as radio tends to be dominated by younger ''in-the-moment stars''.

He continued: ''Radio caters to in-the-moment stars... Nobody that put out records 25 years ago is going to have a No.1. Not Paul, Stevie, Bruce, Mick or Keith. Not Prince, not anyone.

''So if she can get on the radio, we've done damn good. Would we like to have a No. 1? F**k yeah, I'm greedy. But it's not realistic.''

However, LA insisted the singer - who recently released her new single 'Infinity' to coincide with her Las Vegas residency and greatest hits collection - will continue to be successful by releasing more music.

He told Billboard magazine: ''I'm not under any illusion that Mariah should compete with, say, Taylor Swift or Ariana Grande. Our job is to make sure the quality is there. Every artist is one great song away from massive success.

''I don't believe in asking artists to go back and be who they once were.

''And let's not forget that one of Mariah's biggest hits, 'I'll Be There', was a cover. There are many things that Mariah can still do.''