Simon Cowell has admitted he was a 'complete idiot' not to recognize Susan Boyle's star power from the moment she appeared on Britain's Got Talent.

He told British radio that s ''It wasn't a great day, she came on and I thought I don't think this is going to be great, I've just got a feeling here, and she started to sing.

''I didn't think at the time, to be honest with you, that this was incredible. I remember thinking this is great but Piers and Amanda got it more than I did and then when I watched the clip back and I saw the whole story, that is when I thought this is going to be huge and I'm going to look like a complete idiot.''

He also stated former Velvet Underground frontman Lou Reed was ''petty'' for refusing permission for Boyle to perform his song 'Perfect Day.'

Cowell said: ''She was supposed to be on America's Got talent this week. We've flown her over and she is going to perform Perfect Day by Lou Reed.

''Two hours before she is going to perform it we get a phone call. Lou Reed will not allow her to sing Perfect Day.''