Campaigners opposing a new nuclear power station are seeking a judicial review over a "premature" decision to allow woodland to be felled.
EDF Energy wants to build two reactors next to Sizewell B in Suffolk and in September was told it could chop down Coronation Wood on the site.
Together Against Sizewell C (Tasc) said the area was vital for wildlife.
East Suffolk Council said it would respond to the campaigners' challenge in due course.
Plans for the new Sizewell C are due to go before the government's Planning Inspectorate in the first three months of 2020, and then on to the secretary of state.
In September, the council approved plans so that EDF could demolish old buildings on what could become the Sizewell C site, so as not to have an impact on any future "phasing of construction".
As part of the preliminary plans, the 1.6 hectare (four acre) Coronation Wood, owned by EDF, would be cut down to make way for a Sizewell B staff car park and visitor centre.
EDF confirmed it would cut down 220 trees, but said it planned to plant another 2,500 across the Sizewell site.
'Jumping the gun'
Tasc said the woodland was a "treasured landscape" providing a home to badgers, bats and birds.
It was concerned proper investigations into the potential scale of environmental damage had not been carried out.
It had asked the council to delay its decision and accused EDF of "jumping the gun" on the application process.
On 23 December campaigners instructed their lawyers to issue judicial review proceedings at the High Court to challenge the planning decision.
Tasc chairman Pete Wilkinson said the council had "acted in an ill-considered, cavalier manner, without the necessary facts at their fingertips", ignored 125 objection letters and had "ridden roughshod" over the opinions of local people.
A EDF spokeswoman said the company took its environment responsibilities "very seriously" and it believed Sizewell C would "play a major role in fighting climate change" by moving away from the use of fossil fuels.