The Information Commissioner's Office (ICO) has described the use of sound recording in CCTV equipment as "highly intrusive".

A new ICO code of practice outlines key issues which organisations and businesses must consider when routinely capturing images of individuals on CCTV.

The ICO warned that the use of sound recording could only be justified in highly exceptional circumstances.

The decision follows recent research revealing that seven out of 10 individuals oppose the idea of CCTV cameras recording their conversations.

Furthermore, over half of individuals are not aware that the use of CCTV cameras is covered by the Data Protection Act.

"CCTV enjoys a lot of public support and can have benefits such as helping with the detection of crime," said Jonathan Bamford, assistant commissioner at the ICO.

"However, it can also be extremely intrusive, monitoring ordinary individuals as they go about their day-to-day business.

"It is essential that organisations and businesses use CCTV responsibly in order to maintain public trust and confidence and to prevent its use becoming viewed as part of the 'surveillance society'."

The ICO code of practice also provides advice on the retention and use of CCTV images, and outlines circumstances when it would be appropriate to disclose such images, for example to law enforcement bodies in the investigation of a crime.