A row broke out last night over long-awaited improvements to one of the most dangerous roads in Britain.

A leading environmental group labelled proposals to dual the entire length of the A66 across the Pennines where 70 people have died in the last decade as unjustifiable.

Transport 2000 claims a safety study, which recommended full dualling, was over-cautious in estimating the likely casualty savings from small scale improvements such as traffic calming and junction work.

But its view was angrily dismissed by campaigners at the A66 Completion Group, who said the claim flew in the face of all the known facts.