Guidance on people being transported in custody has been reviewed after a man set himself on fire in the back of a police van.

The incident happened after the 42-year-old was arrested in Arbroath, Angus, following a disturbance in which it was reported he had a knife in his possession.

The man was handcuffed and put in the cell cage area in the back of the police van.

An investigation report by Police Investigations & Review Commissioner (Pirc), found that on the way to the Dundee Custody Centre he used a lighter to set fire to a piece of his clothing.

It resulted in an injury to his right arm and he was treated at Ninewells Hospital in Dundee.

A report on the incident was submitted to Police Scotland in May and a summary of the findings has now been published by Pirc.

Before the incident, one of the police officers saw the man with an item he believed was a cigarette lighter in the cell cage. But when he was searched, no lighter was found.

The man was wearing a pair of tracksuit bottoms, which had a side pocket next to the knee, underneath his trousers. This pocket was not searched by the officer who was unaware of its presence.

The Transit van had a passenger seat facing back towards the cell cage, but the officer monitoring the man sat in one of the front forward seats.

Once discharged from hospital, the man appeared in court and was convicted.

The report recommended that Police Scotland should review and procedures for the care and welfare of persons in police custody, particularly in the monitoring of someone put in a 'cage van'.

Police Scotland have now confirmed further guidance on the importance of carrying out professional, effective and diligent searches has been given to officers to reduce the likelihood of a similar incident happening again.

The report said: "Where a cage van is being used for the carriage of prisoners, the escort will ideally occupy the seat nearest the cage so that they may keep the prisoner under observations at all times."

Further advice has also been issued on the risks of handcuffing a person in custody at their front.

Superintendent Norrie Conway said: "Our officers and staff work with commitment and professionalism day in, day out, to provide a high quality policing service for the public, including those in our care.

"They work in challenging situations in real time and when learning opportunities are identified, Police Scotland is committed to supporting officers and staff where they act in good faith.

"We have already reiterated the importance of effective searches and clarified guidance on seating arrangements in vehicles. We will reflect on the PIRC's findings to see if we can do more to improve how we serve the public."