The head of the police complaints watchdog is to give evidence in the Commons over the policing of the G20 protests in London.

Nick Hardwick, head of the Independent Police Complaints Commission (IPCC) will attend the Commons Home Affairs Select Committee on Tuesday.

Three cases, including the death of a man, have been referred to the body.

Mr Hardwick has questioned in the Observer why some officers apparently removed identity numbers from uniforms.

He also said police were "servants" not "masters".

'Expecting trouble'

In relation to his concerns over some officers suspected of removing their identification numbers, Mr Hardwick said: "I think that raises serious concerns about the frontline supervision.

Further footage

Mr Hardwick told the Observer: "What's been important with all these pictures is we have got such a wide picture of what happened.

"I think that is challenging the police. They have to respond to the fact that they are going to be watched, there is going to be this evidence of what they have done."

He also said that typical complainants of police behaviour were from middle-class backgrounds, who did not previously have a jaundiced view of the police.

"If you are Mr and Mrs Suburban who have a good view of the police and think they do a good job, and they stop you and swear at you, then you are shocked and you complain."

The Camp for Climate Action claimed thousands of peaceful protesters were attacked without warning.

Frances Wright, a lawyer acting for the group, said: "What has happened has demonstrated the importance of protesters watching the police at least as much as the police watch them during protests."