Mel C was shocked when Matt Cardle went to rehab.

The former Spice Girl, who is close friends with the 2010 'X Factor' winner and recorded a single with him, insists he is doing ''amazingly well'' since being treated for his addiction to alcohol and prescription pills at London's Priory Clinic at the end of last year, but claims she didn't see it coming.

Mel C exclusively told BANG Showbiz: ''I was shocked, I didn't have any idea, I knew he was under an extreme amount of pressure, but I didn't realise the lengths he was going to, to try and deal with it.

''He will be the first person to say he kept it from everybody, but the thing here is he's dealt with it and it's inspiring for other people that's he's doing really well. I think he's going to go from strength to strength.''

The 40-year-old star was rumoured to have dated the 'Hit My Heart' singer, 30, but insists they are just good friends and she has been supporting him after he got hooked on Valium and was told he could be weeks away from death.

She said: ''He's absolutely brilliant, he's really focusing on the next single and he's got his tour starting in April. I just think all his family and friends are really proud of him for sorting things out before it got too far.''

Meanwhile, Matt has opened up about his time in rehab and says he feels ''sharper and healthier'' than ever.

He said: ''I just thank whoever is looking after me up there that I didn't slip away and I am still here to talk about it.''