Three quarters of drivers who live in central London have failed to register their cars for a discount under the new congestion charging scheme which start in three weeks' time.

Sunday is the deadline by which those due a discount can register for free. Those who miss it will have to pay �10 to sign up.

From 17 February people driving into central London will have to pay �5 per day or face an �80 fine.

However, residents within the charging zone, disabled drivers and those whose cars run on alternative fuel will get a full exemption or a discount of up to 90%, as long as they register.

Weekend use

But only 9,000 out of the 40,000 people who live within the zone have responded to a letter sent by the Mayor of London.

A further 46,414 have registered for blue badges - the disabled exemption - and 220 have registered for an exemption on the grounds that their cars use environmentally friendly fuel.

It is thought many of those eligible for a discount have not registered because they only use their cars at weekends when congestion charging does not apply.

People are keen to use roads where they don't have to pay which will lead to extra congestion on the ring roads Paul Watters, AA

Meanwhile a straw poll by the motoring organisation AA suggested many drivers were unaware of what the scheme entailed.

Around half the 100 drivers in southern England questioned did not know the start date.

Others thought it applied to all motorways feeding into the London area.

The AA's Paul Watters said Transport for London (TfL) needed to do more to make sure those affected were better informed.

Alternative routes

"Some 200,000 motorists drive into London each day, yet many are ill-informed about the scheme, which is the biggest transport development ever to affect drivers in the south of England."

He also claimed the charge would cause congestion outside the central zone.

"One of the most common questions we are being asked is 'Can you give me a route which avoids the charging zone?'

"This shows that people are keen to use roads where they don't have to pay, which, as we have said all along, will lead to extra congestion on the ring roads."