Westminster Energy Secretary Ed Davies was told to "come clean" today over the coalition's dalliance with EDF Energy while claiming that it isn't subsidising nuclear power.
South Scotland MSP Chic Brodie said it was "simply semantics" to say that the government wasn't subsidising nuclear operators.
The SNP politician's broadside came after EDF's chief Vincent de Rivaz suggested that electricity prices could double.
The energy giant's boss told the Sunday Telegraph that EDF's "strike price" - where the government pumps money into a firm if market prices fall below it - could be set between £100 and £140 per megawatt hour.
Current rates are about £50 per megawatt hour, meaning the coalition would have to shovel money to the French-owned company, which heavily relies on nuclear power.
Also known as contracts for difference, these subsidies in all but name have riled anti-nuclear campaigners, who say they violate EU regulations.
Mr Brodie, a former Liberal Democrat, said: "Ed Davey should come clean on just how much new nuclear power would cost ordinary people and abandon his efforts to secure new nuclear, which have disaster written all over them."
A Department for Energy and Climate Change spokesman told the Star there would be "full transparency provided over terms agreed, after a commercial negotiation."