Louis Walsh has mocked Simon Cowell's ''new face''.

Simon, 59, recently unveiled a dramatic physical transformation recently after dropping 20lbs on a vegan diet but his 'X Factor' co-star and close friend Louis, 67, has joked that Simon's changing look is a vast improvement on last year.

He said: ''Sharon Osbourne's got a new face. Simon's got a new face. It's brilliant, he obviously looks after himself a lot. He looked terrible last year. He did, let's be honest.''

However, Louis is not impressed by Simon's weight loss.

He told The Sun's Bizarre column: ''He's lost an awful lot of weight, he looks too skinny now.''

Meanwhile, Simon has been open about his love of Botox in the past and, last year, revealed he had splashed out £2,000 on a Silhouette Soft Lift.

The 'X Factor' judge paid a visit to cosmetic surgeon Dr Jean-Louis Sebagh - known as the ''Picasso of dermatology'' - for a Silhouette Soft Lift, which involved sewing bioplastic-infused thread into the face and neck, to get rid of sagging skin.

He said: ''There's lots of things you can do now. You don't just have to stuff your face with filler and Botox.

''It hurts like hell but it gets rid of sun damage and unplugs all the crap.

''For me now, it's all about having clean skin. If you have clean skin, you look better. But you have to be very careful with some of this stuff.''

While the music mogul has made no secret of the fact he likes to experiment with different procedures, he previously admitted there was a time in the past when he had ''too much Botox''.

He said at the time: ''Hopefully I look better now - I probably did have a little too much Botox a couple of years ago, because everyone on TV has it. Now I have facials, but nothing too extravagant at the moment. I have a girl who comes here and does a great face massage - it's very relaxing. I also had a sheep placenta facial once, which was quite out there. Then Sinitta recommended I try another detoxifying machine, and this thing turned up in my bedroom and it was like something out of Dr Who. It was like a spaceship had landed in my bedroom.''