A Calgary man admits he hit a man over the head with a toilet tank cover but says it was self defence.

Tyler Nolet is charged with the second-degree murder of Kenny Wong.

The F.O.B. gang associate was killed at Cowboys bar in August, 2008.

At the time of the killing, Nolet was a member of a rival gang known as the F-Killers.

Nolet says he didn't intend to kill Wong but acted out of fear for his own life because there were other gang members in the bar. "I was trying to defend myself," the 27-year-old told court on Thursday.

Nolet says he noticed Wong carrying a man purse and feared there may be a concealed weapon inside. Nolet admitted in court he never actually saw a weapon.

Video surveillance from that night clearly shows Nolet striking Wong, from behind, as he sat at the bar.

Despite being challenged by the prosecutor, Nolet insisted everything he did in the bar that night was in self defence.

The trial continues on Friday.