The Algerian man, who has spent two years in prison on fraud charges after being arrested, claimed he was a tourist when he was approached by police officers. His camera phone had more than 90 minutes of video footage of tube stations, CCTV cameras and sensitive locations around London.

The footage, which the police claim was part of a hostile reconnaissance for a possible terrorism attack, has been released to justify the use of anti-terrorism legislation against photographers.

Superintendent Chris Greany of the City of London Police says in a statement: 'I'd much rather justify what we did do in stopping someone than having to justify why we didn't do it against the backdrop of a burning building and a terrorist atrocity. We don't just stop people for a laugh, we're trying to make London safer.'

He adds: 'The cops on the street are aged 21 and 22, it's a big ask for them to identify who is behaving suspiciously and who isn't. It's a difficult balance but the City of London is a terrorist target. We want to set a balance between the challenges of policing and legitimate photography by tourists and the media.'

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