Proposed new underground cables would cause “huge damage” to an area of protected wildlife, the RSPB has said.
National Grid is planning an electricity link between Suffolk and Kent, mostly under the sea, to help deliver on the UK’s net zero targets.
The suggested route would pass underneath RSPB Minsmere near Saxmundham and RSPB North Warren near Aldeburgh.
National Grid said “we give careful consideration” to the environment.
RSPB Suffolk area manager Adam Rowlands said: “Steam rolling through the middle of areas which have been afforded protected status due to their exceptionally high value to nature and wildlife and scenic beauty just makes no sense, especially at such a critical time when we are in a climate and nature emergency and nature seems to be under threat from every direction.
“We strongly urge National Grid to remove these nature-damaging proposals and look at alternative routes which would not heavily impact wildlife.”
National Grid has proposed a route for its EuroLink project, which is a subsea cable between the UK and the Netherlands.
It said it would harness the volumes of offshore wind and power up to 1.8m homes.
Its second project, Sea Link, would build six miles (10km) of onshore cables and 87 miles (140km) of undersea cables linking Suffolk and Kent.
An eight-week public consultation on both projects was due to end on 18 December.
The RSPB said North Warren was a finely balanced set of habitats to species including ducks, swans and geese, while Minsmere was home to woodlark, nightjar, nightingale and the “iconic stone curlew”.
The charity said Minsmere would also be impacted by “huge disturbance” from the planned Sizewell C power station.
Therese Coffey, MP for Suffolk Coastal, launched a petition calling for the Department for Business, Energy and Industrial Strategy and National Grid to review all onshore energy connections along the Suffolk coast.
A National Grid spokesman said: “Our proposals will enable clean electricity to power homes and businesses in Suffolk and across Great Britain, as well as in the long term helping to reduce energy bills and boost progress towards net zero.
“We understand that plans for new infrastructure can cause concern in nearby communities and we give careful consideration to environmental and community impacts.”
He also said it welcomed local communities and stakeholders who shared their views.
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