London, July 17: Just hours after leaving rehab clinic Detox 5 in North Yorkshire, troubled rocker Pete Doherty got into trouble with the cops once again, this time for littering.

The Babyshambles singer boarded a blue minicab and was stopped by the police as soon as they spotted him chucking garbage out of the window in London's Regent's Park.

An onlooker said that the troubled rocker looked really 'sheepish and embarrassed', and that the police gave him a stern warning as they fined him for the offense.

He scrabbled around in his pockets to find papers that could prove who he was. The policeman gave him a stern ticking-off, then issued him with the fine. It looked like he got a severe warning," the Sun quoted the source, as saying.

A police spokesperson also confirmed that the 28-year-old was fined a sum of 100 pounds.

The trip to the clinic is believed to be the beginning of the course that a judge had ordered him to undergo, after the rocker was convicted for possessing class A drugs.