Police are investigating after a gang of youths hurled bottles at four teenagers in a suspected racist attack yards from a police station.

Eye witnesses say the boys were threatened with knives during last night's incident in John Street, Brighton.

They fled when a passer-by intervened, running straight to the police station where they reported the assault.

One of the boys suffered a facial wound during the incident.

Bob Brecher, 53, a lecturer at Brighton University, was walking home when he witnessed a commotion at the Albion Hill end of John Street shortly before 8.30pm.

He said: "There were about 20 children, the youngest couldn't have been more than ten and the oldest 15. They were chasing four black lads, aged between about 14 and 17.

"I yelled to try and stop them and that gave the lads a chance to run off. I was then surrounded by these young thugs. One of them threatened me, saying, 'We've all got knives, where do you think you're going?' I was pushed around by two of them. I would have been daft to hit back."

Mr Brecher went to the police station to report the incident. He added: "It goes to show Labour's racist policies on asylum-seekers and immigration are filtering through. It made me ashamed to be British."

A police spokeswoman today said the report was being investigated.