Tom Brake, a party spokesman on home affairs, was filming with colleagues inside the so-called kettle in the Bank district.

The video has now been submitted to the Independent Police Complaints Commission.

Tom, who represents the Carshalton and Wallington constituency, said: “This video raises concern about the relationship between the police and the media during the G20 protests.

"This journalist was obstructed in his work as we was not allowed to leave the area. This was an attack on the freedom of the press.

“There are clear guidelines laying out how the police should deal with the media: they have to allow them to go about their business."

Tim Gopsill, Editor of the NUJ magazine The Journalist, attended the G20 demonstration as an observer.

Tim said: “"Trapping people in a cage for hours on end was an outrage, whether they were press or not.

"For journalists it meant they couldn't get out to work on their reports, which was an assault on press freedom - journalists should have freedom to leave events as well to get into them."

Last year, a UK parliamentary committee asked the police not to obstruct journalists doing their work during protests.

In its report the parliamentary committee said: "It is unacceptable that individual journalists are left with no option but to take court action against officers who unlawfully interfere with their work.

"Journalists have the right to carry out their lawful business and report the way in which demonstrations are handled by the police without state interference, unless such interference is necessary and proportionate, and journalists need to be confident that they can carry out their role.

"The public in turn have the right to impart and receive information: the media are the eyes and ears of the public, helping to ensure that the police are accountable to the people they serve. Effective training of front line police officers on the role of journalists in protests is vital.

"Police forces should consider how to ensure their officers follow the media guidelines which have been agreed between ACPO and the NUJ, and take steps to deal with officers who do not follow them."

Watch Tom Brake’s video:

21 April 2009