Environment Minister Lord Gardiner has joined calls for National Grid to put more of its cables underground as it creates a new power route across south Suffolk.

The minister wrote to Robert Erith, President of the Dedham Vale Society, saying that the National Grid should not restrict its underground cables on the Bramford to Twinstead route to the official Stour Valley Area of Outstanding Natural Beauty.

He said: "I share your passionate concerns of the significant impact that this option will have for the landscape value of the Stour Valley.

"The government’s formal ‘Planning Practice Guidance’ underlines the importance of this duty and makes it clear that it also applies to development schemes in areas which provide the complementary setting to an AONB and contribute to upholding its statutory purpose.

"The section of the Stour Valley affected by this scheme should come into that category."

South Suffolk MP James Cartlidge said Lord Gardiner's intervention should force the National Grid to rethink its plans for the route of the power lines.

He said: “In National Grid’s proposal to reinforce pylons on the Bramford-Twinstead transmission route, the only undergrounding of cabling that they refer to is where the pylons would go through countryside formally designated as AONB.

"In reality this would mean that most of the route would remain above ground, and many constituents have contacted me to express their alarm at such a prospect.

"However, Lord Gardiner’s letter is quite clear that National Grid has a duty under the Electricity Act 1989 to do what it can to 'reasonably mitigate' the impact of its infrastructure on the natural environment.

“I believe that this is a significant intervention by a Government Minister. I have previously accepted that with offshore wind output growing at such pace there is a case for reinforcing the capacity of the National Grid.

"However, if we have to have continued onshore infrastructure reinforcement then I agree with Lord Gardiner that undergrounding should play a much more significant role.

"While I recognise and very much support the role East Anglia plays in helping the UK move towards Net Zero, I will continue to make the case with colleagues for doing everything possible to avoid the harmful impact of large-scale infrastructure upgrades to the electricity transmission grid.”

A spokeswoman for National Grid said: “We welcome all comments and would encourage all who wish to give feedback to do so. Our current proposals are to put the cables underground in the Dedham Vale AONB and the Stour Valley.

"We will use all such feedback including from both rounds of consultation to inform the proposals that we put forward for planning consent.

"We are very mindful of the matters that have been raised by local people as we develop our plans to help the country achieve Net Zero.

"Later in the year we will be presenting more detailed proposals and will be holding a further round of public consultation.”