Government plans to introduce a road pricing system will only cut traffic if accompanied by strong investment in infrastructure, construction suppliers have warned.

Under the proposals outlined on Monday by transport secretary Alistair Darling, road users may be charged up to £1.34 for each mile in a bid to cut congestion. But the Construction Products Association claims that improved infrastructure is the key to reducing traffic and cutting delivery times for supplies.

Allan Wilén, economics director at the association, said: “What we need is a programme of investment in infrastructure. Then we can start looking at ways to fund that.”

The proposals, based on a feasibility study published last summer, do not make it clear whether businesses would be granted concessions on the charges.