There are 200 congestion cameras
Congestion charge cameras are to be used to fight terrorism, Metropolitan Police Commissioner Sir John Stevens has said.
He said the cameras could prove helpful to anti-terrorism investigations but emphasised they would not be used as a weapon against other types of crime.
Sir John said the cameras, which record car registration numbers, could be used as "part of the equation" to keep tabs on suspected terrorists.
"We hope to get those benefits in terms of cars going in and out and we're looking to do that. It's early days yet but I think potential benefits must be there," he said.
The force needs permission from Transport for London, the organisation that runs the charge scheme, every time it wants to use the cameras.
Congestion charging, which has so far seen a reduction in traffic of around 20% in London, was introduced on 17 February.
Motorists have to pay £5 to enter central London or risk paying a fine of up to £80.
A system of more than 200 cameras has been installed to enforce this.