Policeman off sick runs the line at Elland Road

Officiating at a Premiership football match between bitter rivals not averse to off-the-ball shenanigans would seem to most right-thinking people to be a job from hell. According to the employers of an assistant referee, apparently suffering from stress, it is merely "therapeutic".

Despite being on sick leave from his job at Durham police force, Sergeant Nigel Miller was allowed to work as an assistant referee in front of 40,000 fans for one of the great grudge matches of the season between Leeds United and Manchester United on Saturday.

The game was notable for the volatile reception given by Leeds fans for the return of Rio Ferdinand to Elland Road and a row over whether David Beckham used his elbow in the face of fellow England player Lee Bowyer. The match, won 1-0 by Leeds, could hardly be described as passing without incident.

Mr Miller has not reported for duty since last month although the force said he was expected back soon. Mr Miller, who used to be a trainer for the force's firearms squad, now works for the custody section but is believed to be off work with stress. In 1995, Mr Miller, based in Bishop Auckland, was praised for rescuing two women from the freezing waters of the river Wear in Durham.

The force declined yesterday to say why Mr Miller was off work. "We are not prepared to discuss the reasons for this officer's current absence from work save to say he has a medical certificate from his own GP saying he is unfit for work.

"The officer has been seen by our own occupational health physician and medical opinion suggests the exercise associated with his footballing interests would in fact be therapeutic and help aid his recovery. We expect him to be back at work very shortly."