Carmarthenshire Council has approved an application from Cambrian Renewable Energy Eco 2 for 16 turbines, each standing at 110 metres.

Nearly 500 people objected to the application.

Kate Ashbrook, general secretary of the Henley-on-Thames-based Open Spaces Society, said: "There are so many objections from local people that the Welsh Assembly should refuse planning permission.

"Eco 2 needs consent from the Assembly under section 194 of the Law of Property Act 1925 to erect turbines on common land.

"The Assembly has to be satisfied that the application is of benefit to the neighbourhood," said Ms Ashbrook.

"It is hard to see how they can be when so many from the neighbourhood object to the desecration of their local common."

She said they would continue the fight to save Betws mountain from destruction. She added: "The turbines will be a hideous eyesore on this beautiful mountain.

"It is an area of immense scenic beauty, with terrific views, where people may walk undisturbed.

"All this would be destroyed if the turbines are built here."

But Eco 2 director of projects Chris Williams said the wind farm was backed by commoners.

He added: "The majority of commoners supported the wind farm together with the landowners, who consist of 40 local farmers.

"They found the proposal a significant benefit for them to maintain the mountain."