The details of journeys taken by millions of motorists are to be handed to police under a government “Big Brother” plan to use road pricing technology in the fight against crime.

Police would be given instant access to number plate data from “smart” cameras monitoring congestion in cities and the movement of traffic on Britain’s major roads.

The proposal to pass to police a huge amount of data tracking individual journeys has caused a split between the Home Office and the Department for Transport, which fears that it will set back plans for road pricing.

Plans to enable police to track journeys throughout England and Wales were revealed in a document mistakenly released by the Home Office yesterday.

The disclosure came as the department announced that the Metropolitan Police was to get access to automatic number plate recognition data from 1,500 congestion charge cameras in London to help in the fight against terrorism.

But the document inadvertently released by the Home Office disclosed a much more sweeping plan for the wider use of smart camera technology in the fight against all crime rather than just terrorism.

It also discloses that ministers were warned that the Metropolitan Police plan was likely to cause a “high” level of controversy.

A Home Office spokesman said last night: “The decision to allow the Metropolitan Police access to data held by Transport for London linked to the congestion charge had only been taken after consultation within government.”

He added that any move to allow number plate data to be sent in bulk from third parties to the police to assist crime fighting would only be taken after very extensive consultation across government.

Opposition politicians and civil liberties groups expresed alarm at the wider plans and cautioned that the proposals would give the State unprecedented access to car drivers’ movements.

Nick Clegg, the Liberal Democrat home affairs spokesman, said: “With this unintended act of open government the disingenuous attitude of ministers towards public fears about a creeping surveillance State is revealed for all to see.

“Bit by bit, vast computer data-bases are being made interoperable and yet the Government seems to be running scared of a full and public debate on the safeguards needed to make such information sharing acceptable.”

Mr Clegg accused ministers of using the announcement that the Metropolitan Police was to get real-time access to number plate data from the congestion charge database as a basis for much more far-reaching proposals affecting millions of motorists.

The London plan means that police will know the moment that a suspect vehicle enters and leaves the capital’s congestion zone but the system will only apply for operations involving “national security”.

However, under the plans being studied by the Home Office, police throughout England and Wales would get real-time access to number plate data from cameras operated by the Highways Agency and local authorities. If other cities adopt congestion charging or road pricing based on automatic number plate recognition, police would get instant access to the data. It would allow them to track vehicles moving around the country.

The paper released by mistake discloses that the Home Office sees the deal with the Metropolitan Police as an “immediate solution pending the introduction of planned government agreement on proposed legislation which would allow the bulk transfer of automatic number plate recognition data from third parties to the police for all crime-fighting purposes”.

Number plate data handed over to the police would allow officers to check against an existing “hot list” of vehicles on which there is intelligence. Officers would be able to track vehicles linked to individuals in whom they are interested, the paper said.

It also makes clear that crime analysts would use the data to identify unknown vehicles travelling regularly with a known suspect vehicle, enabling them to identify crime suspects. Offi-cers would also be able to identify vehicles in particular geographical areas after a crime has been committed.

The paper, dated June 4 this year, discloses that the Department for Transport had concerns about the proposal to give Metropolitan Police access to congestion charge data, “linked to wider concerns about pri- vacy and proportionality”. It cautions that even allowing the Metropolitan Police access to congestion charge data on the ground of national security was likely to cause a “high” level of controversy. “Civil rights groups and privacy campaigners may condemm this as further evidence of an encroaching ‘Big Brother’ approach to policing and security, particularly in light of the recent epetition on roads pricing,” it said.

Shami Chakrabarti, the director of Liberty said: “It is one thing to ask the public for special measures to fight the grave threat of terrorism, but when that becomes a Trojan horse for mass snooping for more petty matters it only leads to a loss of trust in government.”

There are 1,500 congestion charge cameras recording number plates in London and a further 1,140 operated by the Highways Agency, including 108 deployed in the West Midlands. Fifty are on the M42.

Times Recommends

• Please help: maimed children of war want their lives back
• Unlocking the cruellest prison
• Prince Charles named in £81m court battle