The photographers were covering protests outside the Greek embassy in London on 08 December when a police officer deliberately obstructed them in their work. The photojournalists, Jason Parkinson and Marc Vallee, claim they were physically removed from any area from which they could document events.

'The police must remember that they have responsibilities towards the media,' said NUJ legal officer Roy Mincoff. 'Even where a protest is itself illegal, the media have a right to report on events and the police should not be taking action with the intention of obstructing journalists in their work.

'There are clear guidelines which discuss how the police should work with the media and officers policing demonstrations need to be made aware of their responsibilities. The police know very well our concerns around cases like this and it's simply unacceptable for our members to continue to have problems when covering protests. Such basic infringements of our members' rights must stop.'

The incident was caught on video, and can be viewed on BJP's blog - 1854.eu.

A Metropolitan Police spokesman has confirmed that the officer featured in this clip 'will be investigated regarding his conduct with a member of the media. There are clear service guidelines that all officers are expected to adhere to that protects the rights of media'.

He added: 'This was a spontaneous demonstration that at points included outbreaks of disorder, which required a response from police.'

It's not the first time that Vallee has been the target of heavy-handed police methods. Back in October 2006, officers allegedly injured his back him to the curb while he was covering the unlawful 'Sack Parliament' protest in London. Vallee also claims to have been repeatedly filmed and monitored when covering other protests.