Questions over security at the headquarters of Norfolk County Council have been asked after an intruder filmed himself and his dog wandering through offices at County Hall.

Four videos posted on YouTube show a man and his dog who spent at least an hour walking through the Norwich building when it was closed on a Saturday, according to the film commentary.

The man smokes and drinks, turns on a computer and a radio, looks at documents on desks and at one point, bumps into a county council worker, who does not challenge him.

In the council's legal department NPLaw, he reads documents he finds on desks and goes into the office of head of law Victoria McNeill, where he rummages around her desk.

He then appears to write Nazi Public Law on a notepad he finds and also draws a swastika and an anarchist symbol.

Elsewhere in NPLaw he hunts for case papers and looks at a number of documents, which he then moves from one desk to another. He also walks through the business development unit, transformation team, democratic services support team, the communications unit, planning, performance and partnerships and wanders into the the office of Mike Jackson, the director of planning and transportation. Commentating on the film footage of his intrusion, at one point he writes an anarchy symbol on a whiteboard and swigs from a can of ginger beer. He also smokes handmade cigarettes, including in the offices of the drug and alcohol action team. When he encounters a worker, he simply says he is making a video tour of County Hall and then carries on with his exploration.

The man starts filming on the top floor of the Martineau Lane building and continues all the way down to the basement, but he does not state how he got into the building. He also does not show how he got out. Mike Brindle, leader of the opposition Liberal Democrat group, said: 'We need to have confidence that the private papers of all who work in County Hall are as safe as possible. This intruder was able to wander the corridors, offices and workspaces of County Hall totally unchallenged for an absolute minimum of 20 minutes. Maybe he just took pictures, but he could have done far worse.'

A spokesman for Norfolk County Council confirmed a security review had been launched, after the council lodged a report with police on Thursday last week.

The spokesman said: 'A full and thorough review of security is under way and commenced last week as soon as we became aware of this incident. The matter is now the subject of legal proceedings. We are unable to discuss current security arrangements for obvious reasons.'

A Norwich man has been charged with racially aggravated harassment following the incident at County Hall. Tom Smith, 27, of Trafalgar Street, is due to appear at Norwich Magistrates' Court on Monday, February 4.