A policeman who was caught on a security camera apparently banging the head of a suspect on a police car has denied assaulting him.

PC Michael Anthony Hughes, 36, is charged with assaulting Adam Lamonby while arresting him in Bournemouth last April.

Weymouth Magistrates' Court was shown a CCTV recording of the officer arresting Mr Lamonby and - the prosecution alleged - "bouncing his head off the back windscreen of his patrol car".

Gareth Evans, prosecuting, told the court that PC Hughes then stood in front of the camera to try to obscure the treatment of Mr Lamonby.

Mr Evans told the court: "A police officer is entitled to use reasonable force during an arrest if they believe it to be necessary.

"On no basis can what the defendant did that night be justified as reasonable."

'Drunk and disorderly'

PC Hughes has denied a charge of common assault and said he was confronted with a baying mob of youths.

But Mr Evans said the group of four men on the video appeared to be calmly waiting for a taxi at the time of the incident.

Mr Lamonby and his friend Shaun Stubbs, who was also arrested, were immediately released by the custody sergeant at Bournemouth police station without charge.

They had been detained for being drunk and disorderly.

The court heard that controller of CCTV cameras in Bournemouth, Simon Trowbridge, recorded the incident after observing the arrest of Mr Stubbs.

Mr Trowbridge sent the tape to the Dorset Police, who launched an internal investigation. Criminal proceedings were then started.