A Bulgarian man accused of stabbing and beheading a British woman denied murder, as his trial began in Spain on Monday.

Jennifer Mills-Westley, 60, was attacked in a supermarket on the Spanish resort island of Tenerife on May 13, 2011 by a man who then fled into the street grasping her head.

Bulgarian Deyan Valentinov Deyanov was arrested as he allegedly tried to flee the scene.

On the first day of the hearing, Deyanov denied murder and said he was haunted by voices.

"Sometimes they (voices) tell me to kill, sometimes they tell me to fight, sometimes they tell me to hit, sometimes they tell me to pray," a female interpreter told the courtroom.

"I ask you to see my client as a sick man rather than a killer," Deyanov's lawyer said.

CCTV footage of the assault was shown in court.

"It might be quite tough evidence, but it is the best way to see how the incidents happened," the prosecutor said.

Presented by Adam Justice