Eddie Mitchell said he was taking general shots of the Hove Town Hall when he was asked by a member of police staff what he was doing.
Mr Mitchell said he told the woman: “I am a photographer taking pictures.”
But because he would not give his name or tell her why he was taking the pictures, he was asked to enter the police station at Hove Town Hall to make a statement.
It was then that two officers detained Mr Mitchell, searched him, and took his camera under section 43 of the Terrorism Act.
Section 43 of the Terrorism Act says: “A constable may stop and search a person whom he reasonably suspects to be a terrorist to discover whether he has in his possession anything which may constitute evidence that he is a terrorist.”
Mr Mitchell said: “What is going on? Any member of the public can take a picture anywhere at anytime, and 99 per cent of police officers know that, and are very good.
“A member of staff in civilian clothing took it upon herself to ask me what I was doing. Then I have to go in and make a statement that I’m taking a general view of a public building,”
Sussex Police has been approached for a comment.