Rocker Pete Doherty has hit out at reports alleging he had continued to use hard drugs while behind bars in a London jail, insisting he has a certificate proving his sobriety. The Babyshambles frontman was released early from Wormwood Scrubs Jail on Tuesday morning, after serving 29 days of a 14-week prison sentence for probation violation.

Last month, British newspaper The Sun published photos of Doherty inside his jail cell and claimed he was still on drugs.

But Doherty, who admits the prison stint was difficult, has blasted the tabloid reports of his alleged heroin use as "rubbish."

He says, "I managed to stay clean. I got my certificate. I was going to Cellotape it to the wall, but they wouldn't give me any Cellotape. Did I take heroin inside? Complete rubbish. The prison didn't release statements - it's their policy to ignore it rather than acknowledge it (the media reports). I was in segregation for the last three weeks. They call it the block. Supposedly I was in debt to loads of big time drug dealers. All I'll say to that is: chance would be a fine thing."

-Pete Doherty Pictures

(This news article provided by World Entertainment News Network)