Traffic levels have fallen since the charge began

Asked whether they thought the �5 charge was working, 74% of businesses questioned said yes, 3% said no and 23% were undecided.

The survey by London First, a business membership organisation which has long supported the charge, is a vote of confidence in the scheme which charges motorists �5 a day to drive into central London.

But with some small businesses on the charge zone boundary seeing takings fall by 15% or more since 17 February, not everyone believes the charge can yet be called a success.

Wine distribution company Cert Logistics is among those businesses benefiting from a 20% reduction in traffic.

It delivers wine to some of central London's top restaurants and hotels and says delivery times have been cut by as much as 50%.

Charge 'should be higher'

One of the company's managing directors, Michael Lainus, said he would like to see the charge tripled to �15.

He told BBC London: "I'm afraid we are seen as a little heretical in our trade but we actually believe the charge should be higher and maybe the area should be larger."

Only 5% of those surveyed felt it had harmed their business.

Most people, 65%, felt the scheme had no impact on their businesses while 30% said there were positive effects.

But the enthusiasm for the scheme was tempered by a mixed reaction to the technology it uses.

Two-thirds of those questioned said they had experienced problems registering their vehicles.