The Freight Transport Association (FTA) has said there is an urgent need for a review of the Severn Crossing tolls.
In correspondence sent to the Welsh Affairs Committee, the organisation has called for a freeze on pricing in 2011 in order to help businesses hit by the economic downturn.
The fact that the road is an essential trade route between England and Wales means that the hikes need to be stopped to help the economy, the FTA claimed.
Commercial vehicles should be able to take advantage of a discounted rate during off-peak hours and credit and debit card facilities need to be introduced, it stated.
Policy manager for Wales and the south-west Ian Gallagher argued that it is "absolutely ludicrous" that struggling firms are being hit by "cynical price hikes".
He added: "Some of our members spend many thousands of pounds on these tolls every month - it is simply unsustainable."
Earlier this year, the FTA called for Westminster to look into the financial effect that the tolls have on businesses in the south-west of England.
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