LONDON —  Rocker Pete Doherty, best known as the on-off boyfriend of supermodel Kate Moss, has been arrested on suspicion of drug possession, police and the singer's spokesman said Thursday.

Doherty, 26, was stopped by police as he drove along a street in west London early Wednesday, said spokesman Tony Linkin.

The Metropolitan Police said officers had stopped a car that was driving erratically in the area. Police said "substances" were found and a 26-year-old man was arrested on suspicion of possessing Class A drugs — a category that includes cocaine and heroin.

The driver was taken to a local police station and later released on bail. He is due to report back next month.

Doherty, former lead singer with indie rockers The Libertines, now fronts the band Babyshambles.

His relationship with Moss coincided with her own well-publicized drug problems. She checked into an Arizona rehab clinic in September after a tabloid newspaper published pictures that allegedly showed her taking cocaine.