OXFORD City Council has been told to justify its plan for recording conversations in taxis in a move that may take the controversial scheme closer to being ruled a breach of privacy.

The Information Commissioner’s Office has served a preliminary enforcement notice on the council over its plans to make all Hackney cabs and private hire taxis it licenses install a sound and video recording system.

The ICO says the compulsory scheme may not comply with the Data Protection Act and has asked the council to submit a written response proving otherwise.

If the commissioner’s office is not satisfied with the council’s response, it can issue an enforcement notice, demanding that the plan is scrapped.

Failure to comply is a criminal offence.

The council wants all new cabs to have the £460 cameras, with the existing 665 vehicles fitted by April 2015.

It has offered to pay £100 towards the cost of each recording system.

The council argues cameras will protect drivers from assaults and allegations by passengers.

It says footage would only be reviewed on request.

The watchdog contacted the council after the Oxford Mail reported on the proposals in November last year.

The ICO’s CCTV code of practice says: “CCTV must not be used to record conversations between members of the public, as this is highly intrusive.”

The scheme was due to start on April 1 but was put on hold by the council because of the watchdog’s intervention.

ICO spokesman Greg Jones said: “The notice relates to our concerns that the scheme may not be compliant with the requirements of the Data Protection Act.”

The Act’s principles include the demand that collection of information should be “not excessive”.

The council has until early next month to respond.

Spokesman Annette Cunningham said: “As a public body, it is right that the council should reflect on the concerns expressed. The scheme has been suspended pending that reconsideration.”

Nick Pickles, director of privacy campaign group Big Brother Watch, said: “It’s time for the plan to be dropped.”

Private hire driver Khalil Ahmed – who collected 273 signatures on a petition against the plan – said: “It’s very positive news.

“We have always argued against the legality of it. It is futile and unnecessary and a waste of ratepayers’ money.”