The Welsh government has announced plans to ban the use of traditional steel pylons to support electricity lines over which it has control.

Plaid Cymru ministers favour burying cables underground instead.

Plans for a network of pylons in the Towy Valley have faced a fierce local backlash with local Plaid politicians speaking out against the proposals.

The company behind the plans, Green Gen Cymru, has been asked to comment but has previously said that undergrounding cables would be significantly more expensive than running them overhead.

Prohibiting the use of large steel lattice pylons for new lines up 132 kilovolts was a Plaid Cymru manifesto pledge before May’s Senedd election.

Launching a consultation on its policy on Friday, the Welsh government said undergrounding electricity circuits could “reduce the visual impact of electricity infrastructure, helping to protect landscapes and local amenity”.

It also said that burying cables could make them less vulnerable to severe weather and could reduce the potential impact on birds and other wildlife.

However, the consultation document also acknowledges that undergrounding is “generally considered more expensive to install and maintain and could create construction impacts during installation”.

The government’s policy would allow for wooden poles or “equivalent, less intrusive infrastructure” to be used to support overhead cables where certain planning tests are met.

Green Gen hoped to build three major power line routes connecting onshore wind farms planned by its sister company Bute Energy with the wider grid network.

It said it would invest nearly £1bn by 2030, with proposals affecting parts of Carmarthenshire, Ceredigion, Powys and Shropshire.

But it had faced considerable opposition in certain communities, with groups representing hundreds of landowners taking the company to court last year.

In a bid to address concerns, Green Gen recently unveiled a “slim and compact” 22 metre (72ft) pylon, designed “with the Welsh landscape in mind”.

The company has consistently said that undergrounding its cables would cost on average 4.5 times more, external than running them overhead.

That would mean an extra cost of £500m for the Towy Usk project between Carmarthenshire and Powys, according to Green Gen.

Welsh Energy Minister Adam Price said: “We know the necessary changes in the way energy is generated and used in Wales will require new grid infrastructure, however, we also know that new infrastructure can impact on the communities and the environment that hosts it.

“We want to see infrastructure that is sensitively designed to minimise impacts on the environment and the communities that host them, while offering the maximum benefits for Wales.”

The consultation, external will run until 15 January 2027.