Professor Andrew Sherry from the Dalton Nuclear Institute at the University of Manchester says that despite this setback, nuclear remains the energy choice of the future.
Greenpeace UK's policy director Doug Parr says the Government needs to reconsider its energy strategy, with a nuclear future now clearly no longer a viable option.
Shadow chancellor Ed Ball claims a confusing energy policy and the Government's economic plans are making foreign firms think twice about investing in the UK.
Professor Dame Sue Ion, a Fellow of the Royal Academy of Engineering, said the decision by RWE and E.ON was a warning to the Government.
The 'Horizon Nuclear Project' looked to develop nuclear reactors at Wylfa in North Wales and Oldbury-on-Severn in Gloucestershire.
The Welsh Government said: "This is disappointing news. The First Minister made it clear that Anglesey remains the best option for a nuclear development and has asked for the full support of the UK Government as we work with Horizon to deliver this investment and secure jobs for workers at Wylfa."
The union Unite is urging the Government to get Project Horizon back on track to help secure thousands of skilled jobs. It had the potential to bring £3 billion into the UK supply chain:
E.ON says despite pulling out of new nuclear it will:
- Continue to develop its £736 million Humber Gateway offshore wind project
- Develop its £120 million biomass plant in Sheffield
- Has invested £1 billion in the past year in the UK
- RWE npower says it has invested £1.2 billion in new renewable energy in the UK in the past three years