WITNESSES are being sought to a 'disturbing' incident in Sandwell that saw a man repeatedly struck over the head by a police officer.

West Midlands Police has voluntarily referred itself to the country's chief police watchdog over the arrest after a video of it went viral on social media.

The video, viewed almost 4 million times, shows the 38-year-old man being struck several times and sprayed with incapacitant spray before officers shut down the recording by closing the door.

The incident happened on Monday, February 25 and while the location has not been disclosed, it is understood it occurred on the Halesowen News' patch.

The Independent Office for Police Conduct (IOPC) this week began an independent investigation into the forced used by officers during the arrest.

The watchdog has appealed for the person who recorded the video - and any other witnesses to the incident - to come forward.

IOPC Regional Director Derrick Campbell said: “The footage showing a man being struck over the head several times is disturbing and I am conscious of the widespread concern it has caused, and the impact on public confidence in policing such an incident can have.

"We need to understand the full circumstances and have started an independent investigation that will include looking at whether the use of force by officers was justified and proportionate.

“Police body worn video footage and statements from the officers involved have been provided by West Midlands Police and will be reviewed as part of our investigation.

"We would urge anyone who took phone footage and/or posted it on social media to contact us.”

West Midlands Police provided a full statement earlier in the week, claiming the footage was edited and that the man had earlier attacked officers with walking sticks.

The statement said: "On 25 February officers were called by a doctor who was conducting a mental health assessment in Sandwell.

"During the assessment, the 38-year-old man became violent and assaulted the doctor with a metal crutch, so police were called.

"The video circulating on social media shows edited footage of officers who attended but does not show the events which lead up to his restraint.

"The full body worn video of the response shows the man attack the officers with his walking sticks injuring three of them.

"Incapacitant spray was used and one officer appears to be using a distraction tactic and a full review of the circumstances will take place to decide whether the use of force was proportionate.

"The man was arrested on suspicion of assault and taken into custody.

"He was medically examined while in custody and he had not received any injuries. He is currently receiving treatment in a mental health facility.

"Three officers sustained various injuries to their arms, heads, face and hands while two officers were treated for the effects of the incapacitant spray. The doctor sustained a minor arm injury."

Head of the force’s Professional Standards Department, Chief Superintendent Chris Todd added: “We do not underestimate the impact this video has on the public’s confidence in policing.

"On first view, the video is really shocking and we need to understand the full context of what the officers were facing.

“As well as the IOPC referral, we are consulting with key community members.”