Anti-terrorist police will be able to use London's congestion charge cameras and automatic number-plate recognition system routinely and in real-time to track suspect vehicles throughout the city centre.
The move follows the use of Transport for London's 1,500 cameras to reconstruct the movements of vehicles in the abortive car-bomb attacks in the Park Lane area on 29 June.
A Transport for London (TfL) spokesman said, "Transport for London is fully prepared to support the Metropolitan Police's request for routine access to data from London's Congestion Charging camera system for national security purposes.
"We have examined the technical issues arising from this proposal, and are finalising protocols to ensure the swift and secure transfer of the data in question.
"In allowing for this access, the Home Office has exempted congestion charging camera data from the requirements of the Data Protection Act 1998."
A spokesperson for privacy watchdog Information Commissioner's Office said, "We recognise the importance of tackling the current level of terrorist activity, which clearly poses a threat to national security. The Data Protection Act should not stand in the way of this.
"There is an exemption that exists for use in exceptional circumstances where the safeguards in the act need to be set aside for reasons of national security.
"It is for the Home Secretary to judge whether an exemption certificate is required, but we have been engaged in discussions with the Home Office to ensure that any exemption certificate is not drawn more widely than is necessary.
"The provisions relating to an annual report to the Information Commissioner are a helpful step towards ensuring that the use of TfL camera data remains subject to a degree of scrutiny."
Last week New York City announced plans for a £45m CCTV scheme to monitor suspected terrorist vehicle and pedestrian traffic in Lower Manhattan.