Sizewell C opponents to challenge High Court approval decision

The planned plant is expected to cost about £20bn

Campaigners opposed to the Sizewell C nuclear power plant are to appeal against a High Court ruling which said approval of the plant was lawful.

Together Against Sizewell C (TASC) said it would argue that Judge David Holgate was "wrong in law" when he dismissed their application for a judicial review of the government's approval in June.

Lawyers for TASC said the ruling was "legally flawed" in numerous respects.

The Department of Energy has been contacted for comment.

At a hearing in March, lawyers for the group of residents said the government had not considered "alternative solutions" to meeting its energy and climate change objectives, as well as the impact of providing an "essential" water supply for the plant, which would be next to the existing Sizewell nuclear power plants on the Suffolk coast.

However, Judge Holgate dismissed the challenge and said there was "nothing artificial or unlawfully limiting" about a policy aimed at providing a mix of solar, wind and nuclear power.

He also found the approach to the water supply, which would be dealt with under a separate process, was lawful.

TASC said it believed it was clear that a desalination plant would be needed to guarantee a permanent water supply for Sizewell C and it was not considered in the original decision by then Business Secretary Kwasi Kwarteng.

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In its application for a judicial review, TASC said the issue of a water supply should not have been treated separately and should have been part of the power plant application.

TASC also argued the judge was wrong to conclude there was evidence the power station would be ready to contribute to electricity generation by 2035. It said evidence for this was "threadbare".

The group said the judge also did not deal with their complaint that the site would be clear of nuclear material by 2140, which they said was not likely to happen until a much later date.

The site for Sizewell C, near existing nuclear buildings on the Suffolk coast

TASC chair Jenny Kirtley said: "It is imperative we appeal Judge Holgate's perverse sanctioning of Sizewell C even though the proposed nuclear plant does not have a guaranteed mains water supply, without which it cannot operate.

Paul Collins, chair of a separate campaign group called Stop Sizewell C, said: "We are fully committed to supporting this appeal and we believe the issues speak to critically important points of principle.

"How can it be right to allow a nuclear power station that has no identified potable water supply, in the UK's driest region, to go ahead?"

Rowan Smith, of Leigh Day solicitors, said they considered the High Court ruling "legally flawed in a number of respects" and were hopeful that the Court of Appeal would grant permission for another hearing into these extremely important issues."

A spokesman for Sizewell C said: "We have a clear plan to supply water to the power station which was scrutinised in detail by the government before it granted our development consent order last year.

"Two previous attempts by TASC to apply for judicial review on this issue have been firmly dismissed by the High Court and we will robustly defend our position in any further legal action."