This morning, Smith, an award-winning architectural and construction photographer, was taking photos of a church in the City of London. Next to the church was the Bank of America - Merrill Lynch building, from which a security guard emerged, Smith tells BJP.

'He asked what I was doing, and I just told him that I was taking pictures and didn't have to tell him anything at all,' says Smith. At that point, a second security officer came up to Smith and asked for his personal details, which the photographer refused to provide, at which point the guards called the police

Three police cars and one vans arrived on the scene with up to six armed police officers detaining the photographer. 'They were responding to an incident involving a male at reception who refused to leave, which was not true,' Smith tells BJP.

'I failed the [police] attitude test,' he says. 'I thought the pressure was off after last week's events. I even showed one police officer the front page of The Independent, and he told that he had seen it but that "we can still stop you under Section 44".'

To prevent being searched by the police officer, the photographer was forced to give his personal details. He received a stop and account form and was let go.

Smith is an Australian-born photographer, but he has been living in London since 1983 and 'has an extensive knowledge of London's architecture,' his personal website says.

The incident comes days after the Association of Chief Police Officers sent a memo to all police forces around the country informing them that they 'should not be stopping an searching people for taking photos.' The memo continues: 'There are no powers prohibiting the taking of photographs, film or digital images in a public place.'

The memo was sent after an Independent journalist was stopped for taking a picture of the House of Parliament. The incident caused a media blitz, with newspapers such as The Independent, The Daily Telegraph, The Guardian and Daily Mail, as well as the BBC publishing articles on the issue of public photography.

UPDATE 1.00pm: A spokeswoman for the City of London Police is expected to get back to BJP with an official comment. Check back for more updates.

UPDATE 2.45pm: A security official at Merrill Lynch, talking to Smith's wife Leanne Tritton of ING Media, has said that Smith was not considered to be a terrorism threat. However, it declined to comment further claiming that he wasn't 'at liberty to discuss our security policy'.

A spokeswoman for Merrill Lynch has yet to come back to BJP with an official statement.

UPDATE 3.30pm: A spokesman for the City of London Police has told BJP that the police intervened after 'security staff at a City bank reported concerns over the apparently hostile behaviour of a man taking photos of their staff. When questioned by officers, the man declined to give any explanation. He was therefore informed that, in light of the concerns of security staff, and in the absence of an explanation, he would be searched under Section 44 of the Terrorism Act 2000.'

The police add: 'After the man's bag was searched, he gave his details and explained he was a freelance photographer taking photos of buildings. Once this explanation was received, there was no further action.'

However, Smith has denied he took photographs of staff. He tells BJP: I wasn't photographying staff, and my hostile behavior was simply that I refused to give my ID to the security guard.'

He continues: 'I thought this was over, but it isn't. And I'm sure tomorrow someone else will face the same situation. Of course the police are going to take the side of security guards. The guards are briefed to look out for suspicious people.'