Business Secretary John Hutton is due to announce a decision on an expansion of nuclear energy tomorrow. But an academic report has accused its public consultation last year of being flawed and misleading.
Greenpeace says it is considering dragging the Government back to court.
"The government was in error in asking the public for a decision 'in principle', when the core 'what if' issues were not consulted on in any meaningful way, or resolved in practice," the academics from universities including Oxford, Warwick, Sussex, Newcastle, Cardiff and Manchester conclude.
"These issues include nuclear fuel supply and manufacture, vulnerability to attack, security and nuclear proliferation, radiation waste, radiation risk and health effects, reactor decommissioning, reactor design and siting," they added.
Greenpeace executive director John Sauven said, "For such senior insiders to be so critical of the consultation process is a deeply troubling commentary on the Government’s approach to this issue, and as the report reveals, nuclear power could only reduce the UK’s CO2 emissions by 4% by 2025 - too little, too late.
"Our lawyers are looking at this report and will also examine the Government’s decision on new nuclear build with great interest. We won’t be rushed into a decision, but nothing has been ruled out at this stage."
The main issue for the group of academics is disposal of waste from the new nuclear plants.
"The government consultation documents said this issue had been resolved. That is simply not true," said Paul Dorfman of Warwick University, one of the report's authors.
CoRWM, the independent Committee on Radioactive Waste Management, said in 2006 nuclear waste, which remains toxic for centuries, should be kept forever in a specially built safe storage facility deep under ground.
But while the government pointed to this as the solution to waste from any new plants, CoRWM said it only meant this solution to apply to waste from Britain's old military nuclear programme dating back to the 1950s, so called legacy waste.
The academics also accused the government of glossing over security considerations, the true costs of nuclear and alternative renewable energy sources, the availability of uranium fuel and the siting of new nuclear plants given sea level rises due to global warming.
Of course, a government green light is not actually necessary -- there is no legal barrier to any utility now opting to build a nuclear plant, although there is a lot of planning red tape.
"Although the government has said no public money will be involved in any new nuclear plants, a positive declaration must indicate government commitment in the final event and that can only mean taxpayers' money," said Dorfman.
The report notes that the new nuclear plant being built in Finland, touted by pro-nuclear adherents as a model for the way forward, is not only two years behind schedule but already 50 percent over budget, a fate it suggests would be in store for new plants in Britain, to the detriment of alternative power sources.
The Business and Enterprise Department says the Government believed the consultation was an "open, fair and full" process.
A spokesman said, "We have received 2,700 responses from the extensive consultation, which included public meetings across the UK, a written consultation document and a website. Time is pressing. Consulting indefinitely is not an option."
In Wales the Assembly Government is also sceptical about the need for new nuclear power stations - but with major energy decisions reserved to Westminster, it is powerless to block them.
Ministers in Cardiff Bay nevertheless "strongly support" an extension to the life of the Wylfa site on Anglesey, due to be decommissioned in 2010.
The site in the constituency of Deputy First Minister Ieuan Wyn Jones is of "economic importance", the WAG said.