Mr Prescott said he was satisfied that the benefits of the scheme outweighed the disadvantages, and that it would be in the public interest to allow it to proceed.

Conservationists, including the Snowdonia Society, have opposed the extension of the railway, on the grounds that it would damage the environment.

John Prescott gives go-ahead

Mr Prescott announced in April that he was "inclined to grant the powers" the Ffestiniog Railway Company needed to reconstruct the railway.

But he said he wanted the company to undertake a detailed survey of the rock faces in the vicinity of the Aberglaslyn tunnels.

Since then, the developers had accused the local planning authority, the Snowdonia National Park authority, of delaying tactics in their response to Mr Prescott's proposals.

No "unacceptable harm"

Mr Prescott made the announcement after saying he had carefully considered reports by consultants as well as one by the Welsh super-utility company Hyder on behalf of the Snowdonia National Park Authority.

"I am satisfied from this information that the railway can safely be taken through the National Park without causing unacceptable harm to the environment," he said.