Dr William Gillan, who is in charge of the Department of Transport's motorway tolling project, said it would be five to six years before any system would be ready to use. He made the announcement at the Transport Research Laboratory at Crowthorne in Berkshire, which is conducting tolling trials.
After 10 more weeks of the trials, ministers will decide whether to proceed with tests on the M3 in Hampshire. If approved, motorists could be invited to help by having on-board equipment put into their cars, although the trial will not involve anyone having to pay any charges.
A number of companies were initially involved in technology trials but only two now remain and the timetable for the scheme's possible introduction has slipped considerably.
"I don't think it matters that the timetable has slipped a bit as we have been able to make so much more of the trials we have conducted here," said John Watts, a junior transport minister.
The Government has not set the price that drivers would have to pay - but has said that any money raised would be used for motorway maintenance.
Electronic tolling was first suggested by the Government in 1993, with possible toll charges of 1.5p-a-mile for cars and 4.5p for lorries.
Systems from two companies - GEC-Marconi and Bosch Telecom - were demonstrated. Both devices rely on antennae placed on overhead gantries to pick up signals from vehicles installed with tolling technology. The systems tested use smartcards - a kind of constantly rechargeable phone card - mounted on the windscreen to bill the driver.
Bosch said that at present its system had a failure rate of about one in 10,000 vehicles, but was hoping to improve this to one in a million.
Information gathered by the roadside can be passed to regional or national centres. Anyone passing through illegally - with no credit on their card - could be filmed and later penalised.
Road tolls have been tested in California, Hong Kong, Singapore and Germany.
According to Dr Grant Klein, editor of the Intelligent Highway, a trade magazine: "Britain is well behind the rest of the world. The best German systems were not even considered in the trials today."Reuse content