London's congestion charging has cut traffic numbers

London mayor Ken Livingstone has seen the �5 road toll cut traffic and reduce journey times in central London.

The idea could target suburban traffic hotspots and arterial roads such as the A12 in east London.

The bigger area would be monitored with satellite-based technology and could be in place by 2010.

Mr Livingstone has already raised the possibility of charges for motorists driving to Heathrow, and an expansion of the congestion charge zone westwards to cover Kensington and Chelsea is in the middle of a consultation process.

CONGESTION CHARGE FACTS There are now 60,000 fewer car journeys a day in central London Traffic delays inside the congestion zone are down 30% Journey times have fallen by 14%. The charge is set to raise �68m for public transport in 2003 It is hoped in 2005 the scheme will raise �100m

The idea includes charges for any journey within the greater London area, according to the time of day and location.

And a team of experts at Transport for London (TfL) believes that, given funds from central government, such initiatives could be operational in just six years.

They say that while current camera technology has proved sufficient for the present charging area and for the proposed western extension, alternatives such as digital cameras and satellite-based technology are to be examined.

A TfL spokesman told BBC News Online: "This is just an idea at the moment but we want to bring the benefits central London has seen, as a result of congestion charging, to other areas of London affected by heavy traffic."

While the present system - introduced on 17 February 2003 - operates between 0700 and 1830 on weekdays, tolls elsewhere might be levied at different times of the day and at different days in the week to cope with specific problems.

Damian Green, shadow transport secretary, said: "If Ken Livingstone starts trying to tax every motorist who drives into the Greater London area it would be a huge issue for the national economy, not just the London economy."