LONDON (AP) — UK detectives are appealing for witnesses who might have seen a group of youths attack a teenage asylum-seeker in the London borough of Croydon.

The attack left the 17-year-old Iranian Kurd in serious but stable condition in a London hospital.

Detective Sergeant Kris Blamires said Saturday the victim was at a bus stop with two friends when approached by about eight youths. Blamires says the youths chased the 17-year-old upon learning that he was an asylum-seeker and delivered repeated blows to his head. The teen's friends managed to get away.

British police say hate crimes remain under-reported. London's police force has increased the number of specialist investigators by 30 percent in the past two years, with more than 900 dedicated to investigating such attacks.