A former Power Rangers actor charged with stabbing his flatmate to death with a sword has pleaded not guilty to murder.

Ricardo Medina could face 26 years to life in prison if convicted for the attack.

Prosecutors say Medina stabbed Joshua Sutter several times in the abdomen in 2015 at their house in Green Valley, a mountain town north of Los Angeles.

The two men had allegedly been arguing over Medina's girlfriend.

Authorities said after the attack, Medina called the emergency services and waited for police to arrive.

The actor played the Red Lion Wild Force Ranger in Power Rangers Wild Force in 2002.

He also provided the voice for the character Deker in Power Rangers Samurai in 2011 and 2012.