Road congestion can be reduced by increasing freight capacity across the rail and water networks, a pressure group has argued.

The Campaign for Better Transport (CBT) has conducted new research which it says contradicts the government's conclusion that the benefits of moving freight off the roads would be minimal.

CBT looked at specific routes that tend to see increased congestion resulting from heavy goods vehicles (HGVs), which, it argues, makes the study more accurate than the government's approach of taking a national average.

Congestion on the routes - particularly those leading to ports - could fall by up to 25 per cent if the amount of goods moved by rail and water was raised by 50 per cent, the CBT found.

Freight on rail manager at the body Philippa Edmunds said the government has "underestimated" the benefit rail freight could have and called on it to consider the "congestion, safety and pollution benefits" of moving HGV traffic to rail and water when drawing up policies and allocating spending.