British rapper Dappy lashed out at a fan in an unprovoked attack during a guest appearance at a nightclub in England, a court has heard.

The former N-Dubz star is accused of assaulting a reveller during an altercation outside Chicago's nightclub in Chelmsford, England in February (14).

He arrived for the first day of his trial at Chelmsford Magistrates' Court on Wednesday (18Jun14), and the court heard how the 27 year old allegedly hit out at a reveller in the club's smoking area without provocation during a paid appearance at the venue.

Prosecutor Jaqueline Carey said, "When the defendant lashed out, he was not under any threat or any perceived threat of violence.

"The Cctv suggests he had no genuine and honest belief that he needed to use force to defend himself."

The star, real name Costadinos Contostavlos, denies one count of assault by beating.

Dappy had some moral support in court from British comic Jim Davidson, who turned out to watch the first day of the trial from the gallery. The pair grew close during their stint on U.K. reality Tv show Celebrity Big Brother earlier this year (14).

Outside the court, Davidson said, "Dappy is a good friend of mine. We became close on Big Brother. I don't know what's happened in this case but I'm just here to show him my support."

The trial continues.