Tributes poured in on Sunday for a teenage actor who was stabbed to death during a fight outside a pub that left three other men with serious knife wounds.

Robert Knox, 18, was fatally wounded during the "large disturbance" outside the Metro Bar on Station Road, Sidcup, Kent, in the early hours of Saturday morning.

Friends and relatives left bunches of flowers outside the bar, and a stream of messages were posted on social networking Web site Facebook and the International Movie Database Web site.

The teenager had a small part in the forthcoming film Harry Potter And The Half-Blood Prince.

His parents Sally and Colin Knox, of Maidstone Road, Sidcup, said in a statement: "Rob was kind and thoughtful and would always help out others - he would always spend his last penny on other people instead of himself.

"The life and soul of the party, he was very outgoing, loved sports, and would always strike up a conversation with people.

"He was respectful to others and adored by all his family and friends. He was (an) asset to the family."

Three of his friends also sustained serious injuries in the incident: a 21-year-old was stabbed in the neck, a 16-year-old in the chest and a third man, aged in his late teens or early 20s, sustained stab wounds to his hand.

The 21-year-old is still receiving hospital treatment, while the other two have been discharged.

A fifth man, 21, was taken to hospital suffering facial injuries. He was later discharged, and has been arrested on suspicion of murder.

Scotland Yard said they did not believe the incident to be gang-related.

Knife crime has blighted London in recent months.

Earlier this month, a man was knifed to death on Oxford Street, one of the busiest shopping areas in the country, and 16-year-old Jimmy Mizen died after his throat was slashed after declining to become involved in a fight with a man in a bakery.