Bats are very vulnerable to disturbance of their habitat, and have been in decline in the past few decades, that's why they are protected by law

Friends of the Earth

But Councillor Hilary Cox, cabinet member for the environment on Dorset County Council, said the authority had worked hard to limit damage in the area.

"But we are also concerned about the human environment.

"The sooner this road is built, the sooner the quality of life for hundreds of people living along Dorchester Road and Preston Road will be improved."

She described the escalating costs of feasibility studies and consultancy fees as "scandalous".

The road is aimed at easing traffic congestion into Weymouth.

'Environmental damage'

Construction project manager Rod Turner said: "We have the backing of the people of Weymouth for this road.

"It will be used by buses, cyclists and for access to railways as well."

But Mike Birkin, from Friends of the Earth, said the development was just the "latest evidence" of potential harm to the environment.

"It's a very environmentally damaging scheme.

"Bats are very vulnerable to disturbance of their habitat, and have been in decline in the past few decades, that's why they are protected by law.

"I don't see why Dorset County Council would expect to be outside the law."