The protest in Suffolk came days after ministers delayed a decision on plans for the new plant.
Carrying banners that read “chaos coast coming soon”, “EDF-off” and “we don’t want to be beside the C”, the crowd marched from Leiston to Sizewell beach.
The demonstration took place days after ministers deferred a decision on whether to grant development consent by six weeks.
Tidligere denne uken, the Department for Business, Energy and Industrial Strategy set a new deadline of July 8 as it seeks more information on issues such as water supply.
Campaigners say the delay is a recognition of the project’s problems including water supply, transportere, coastal erosion and biodiversity.
Alison Downes of Stop Sizewell C said: “A decision to go ahead with Sizewell C would be a wrong decision.
“EDF has clearly not taken this community with them, and the Government has totally betrayed the faith of local people in due process by repeated commitments to Sizewell C when it doesn’t have planning consent, let alone a final investment decision.”
Adrian Ramsay, co-leader of the Green Party, sa: “Building a nuclear power station with the kind of subsidy the Government is talking about will lock in raised electricity prices for years to come.
“Renewably generated electricity is now far, far cheaper and will deliver far more sustainable jobs for Suffolk people and its independent businesses than this expensive white elephant.”
The large-scale Suffolk station is part of a fleet of new nuclear power plants at the heart of the Government’s energy strategy, in which Prime Minister Boris Johnson last month set out aims to boost new nuclear power, offshore wind and hydrogen.
I januar, the Government announced £100 million of funding to support Sizewell C’s continued development, with the move aimed to attract further financing from private investors.
If built, Sizewell C would power the equivalent of about six million homes.
A spokesperson for Sizewell C said nearly 60% of people in east Suffolk are in favour of the plans to build the plant, according to an ICM Unlimited poll.
sa de: “Sizewell C will deliver 1,500 apprenticeships and 7,900 jobs at peak construction with at least a third of the workforce coming from the local area. Once the power station is operational there will be 900 rewarding skilled local jobs.
“We are committed to ensuring Sizewell C brings a positive legacy for local people for generations to come.”
Sizewell C’s construction is expected to cost around £20 billion and it would be a near-identical replica of Hinkley Point C, the plant currently under construction in Somerset.
A spokesperson for Sizewell C added: “Our plans for Sizewell C will lead to a 19% increase in local biodiversity. We are not building on any land owned by RSPB Minsmere. Where a small part of our boundary meets RSPB land, we are creating a new area of wetland to allow wildlife to thrive.
“We will limit construction when necessary to reduce noise and we will use directional and low-level lighting. We are confident our plans will not have an impact on this important nature reserve.”