The ICO has launched a consultation on changes to its existing code of practice for using CCTV, published in 2000.
"CCTV must not be used to record conversations between members of the public as this is highly intrusive and unlikely to be justified," said the proposed guidance for organisations which use the technology. "You should choose a system without this facility if possible. If your system comes equipped with a sound recording facility then you should turn this off or disable it in some other way."
Some CCTV operators have begun to include audio in their CCTV use. Some local authorities have begun fitting speakers beside cameras so that operators can admonish wrongdoers observed on camera in real-time.
The ICO said that some limited use of audio should be permitted. "The use of audio to broadcast messages to those under surveillance should be restricted to messages directly related to the purpose for which the system was established," it said.
"Audio based alert systems (such as those triggered by changes in noise patterns such as sudden shouting) may be acceptable subject to sufficient safeguards," said the guidance. "Two-way audio feeds from ‘help points’ covered by CCTV cameras will be acceptable where these are activated by the person requiring assistance."
The UK has more CCTV cameras per head of population than any other country in the world, and Information Commissioner Richard Thomas has previously warned that the UK is becoming a surveillance society without sufficient debate about what that involves.
"It is clear that use of 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 be extremely intrusive, putting law abiding people under surveillance. It is essential that the public is confident that CCTV is being used responsibly and for a proper purpose."
Most CCTV use is regulated by the Data Protection Act, and the guidance from the ICO is designed to help operators comply with the Act.
The consultation process is open for submissions and the closing date for responses is 31st October.