The Deputy Prime Minister came under attack from the Tories after he said that the charges would not be "intro-duced overnight" and "only on balance".
John Redwood, the Torytransport spokesman, said the levy amounted to a "war on the motorists, already unfairly burdened" by the Government.
Mr Prescott insisted no local authorities would be forced to charge drivers for entering town and city centres. He said: "Carrying on as before would be the most anti-motorist policy of all. All I'm doing is improving the choice for the motorist. I can't force local authorities, I have no intention of doing so."
Speaking during resumed debate on the Queen's Speech, he stressed that any money raised from congestion taxes would be reinvested in public transport. Under the plans, part of the Transport Bill unveiled in the Queen's Speech, councils would also be allowed to introduce workplace parking fees. Mr Prescott said everyone, including business leaders, recognised that the economic and environmental damage caused by congestion was unacceptable.
But Mr Redwood said: "The answer to congestion is more capacity - we need more capacity on public transport as well as maximising the use of existing main roads and improving some of them. We all know taxing the motorist off the road does not work."
During the debate, Labour backbenchers also fired the first warning shots of a forthcoming rebellion over plans to part-privatise the national air traffic services (Nats). Gavin Strang, a former transport minister, warned that the sell-off would be a "great mistake". Britain was a "world leader" on air traffic control, with an excellent record of investment, he said. "I have no doubt that there are many Labour MPs who are still trying to persuade ministers not to go down the road of the privatisation of Britain's air traffic control." With the sums available to the Treasury, the Government easily could justify improving on past investment rather than opting for a sell-off, he said.
"The British public will not believe that the privatisation of Nats is being put forward to enhance safety. The airline pilots are against it," he said.
The Government has already been warned it would face "the mother of all rebellions" over the contentious proposals, particularly in the wake of the Paddington rail crash.
Dr Strang claimed the proposed privatisation was also a potential threat to national security. "If terrorists attack an aircraft above Britain or there is an attack by foreign jets, the security services have to be in a position to seize control of the air traffic control system. I do not think that there is any question that the reason why other countries, including the US, have not privatised their air traffic control systems is for reasons of national security."
Mr Prescott said the Government would "never compromise" on safety. "These measures will help enhance one of the most robust systems of aviation safety regulation in the world," he said.Reuse content