Troubled British singer Pete Doherty was freed from jail Tuesday after serving just over four weeks of a 14-week sentence for breaching a probation order imposed for a string of drugs and driving offences.

Wearing a suit and tie and puffing on a cigarette, the former boyfriend of supermodel Kate Moss said after leaving Wormwood Scrubs Prison in London that he was looking forward to drinking a rum and coke and spending some time with his pet cats.

Doherty (29), the lead singer of Babyshambles and the now defunct Libertines, described prison life as "a lot of gangsters" and showed the waiting media a certificate confirming he had passed a drugs test while inside.

"Well, I knew it was going to be a bit rough to start with, with the overcrowding and the medical facilities although they do their best — they are good, they can't really cater for the average junkie," he said.

After borrowing a reporter's mobile phone to call for a lift home, he jumped into a friend's car and was driven off.

Doherty was jailed for drug use and missing appointments with probation officers.

The prison sentence forced Doherty to reschedule a performance at the Royal Albert Hall scheduled for 26 April. He is due to appear at the Glastonbury festival at the end of June.