An MP who was among protesters corralled behind police lines at the G20 demonstrations has called for an investigation into whether the police deliberately incited the crowds.

Tom Brake, Lib Dem for Carshalton and Wallington, says he was informed by people in the crowd that two men, believed to be two plainclothes police officers, had thrown bottles at the police and had encouraged others to do the same.

Shortly afterwards they then passed through a police cordon after presenting their ID cards, he said.

The MP raised the fresh allegations when he gave evidence before Parliament’s joint committee on human rights on Tuesday.

He said: “When I was in the middle of the crowd, two people came over to me and said ‘There are people over there who we believe are policemen and who have been encouraging the crowd to throw things at the police’.

“But when the crowd became suspicious of the men and accused them of being police officers, the pair approached the police line and passed through after showing some form of identification.”

Mr Brake was following the protests as a legal observer when violence broke out between police and protesters in Moorgate.

He was kept inside the police cordon for five hours, along with bystanders, peaceful protesters and even those in need of medical attention.

At the time he called the situation “one of the scariest experiences of my life”.

Mr Brake has produced a draft report of his experiences for the human rights committee, after receiving written statements from people in the crowd.

The Independent Police Complaints Commission said it had no record of complaints involving the use of police agents provocateurs.

A Metropolitan Police spokesman said: “We would never deploy officers in this way or condone such behaviour.”

The use of plain-clothes officers in crowd situations is considered a vital tactic for gathering evidence.

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