The Blackdown Hills are an area of outstanding beauty

The A358 through Ilminster to the M5 at Taunton will be dualled to protect the Blackdown Hills, an Area of Outstanding Natural Beauty.

A plan to widen the A303 through the Hills, supported by business leaders in Devon and Cornwall, was rejected.

Friends of the Earth told the BBC the A303 plan "would have caused enormous damage to the area, noted for its remoteness and tranquillity."

Mike Birkin, from Friends of the Earth South West, said: "We are delighted with Mr Darling's decision.

"A dark shadow has been lifted from one of England's finest natural areas.

This vital improvement is key to the continued prosperity and development of the whole region John Underwood Missing Link

"The A358 route is far from perfect, but it's the lesser of two evils."

However, the group stressed that road building was not the "answer to Britain's transport problems".

The route will cost about �248m, �90m less than the projected cost of dualling the A303. No start date has yet been set.

The Missing Link group, set up to campaign for an early decision on the scheme, also welcomed Transport Minister Alistair Darling's decision.

Group member John Underwood said: "We are delighted. This vital improvement is key to the continued prosperity and development of the whole region - not just of Taunton.

"We believe the A358 has always been the obvious choice. It delivers what the South West needs and spares the Blackdown Hills from destruction."

Devon County Council called the decision, also condemned by some Devon and Cornwall business leaders, "a major blow to the region".