POLICE today appealed for help after a man was knocked unconscious and into a river during a robbery.

The incident happened in the Riverside Park area of Southampton as the 51-year-old man walked along the riverbank.

Officers say he was stopped by a woman standing by some bushes. She was holding a cigarette and asked him for a light.

She positioned herself so the man had his back to the trees and, as he pulled out a lighter, he received a blow to the right hand side of his head, just above his ear.

The next thing the man remembers was waking in the narrow stretch of river from which he had to crawl free.

The man, who is Polish and unable to speak any English, managed to get out of the water on the other side where he remained throughout the night, according to officers in Southampton's robbery investigation team.

He had been walking home to West End when the attack happened.

Pc Claire Lyons, investigating the robbery, said: "This was a very serious incident and we need to find those responsible. The victim sustained serious injuries but is very lucky considering he ended up in the river."

The woman was white around 5ft 3in, up to 17 or 18 years old, with shoulder-length dark curly hair and of normal build. She was wearing a cream coloured top which was possibly a sweatshirt, and blue jeans and tall brown boots.

Anyone with information about the incident, which happened at about 9.30pm on Saturday night, is asked to contact the robbery investigation unit based at Hulse Road on 0845 045 4545.