Peter Hain has broken rank with the Cabinet to express doubts about building new nuclear power stations.
Mr Blair has raised the prospect of new nuclear power stations
Tony Blair is thought to favour nuclear after he said the issue was "back on the agenda with a vengeance".
Mr Blair was accused of pre-empting the government's own energy review - a charge he denied.
Mr Hain said if there had to be nuclear power it must work without huge public subsidy, which should be spent on renewable energy instead.
The Northern Ireland secretary's remarks to Newsnight will be seen as an attempt to curry favour with the Labour's left - angered by Mr Blair's apparent enthusiasm for nuclear power.
They also are thought likely to trigger speculation about his ambitions to be Labour's next deputy leader.
Mr Hain said: "If there has to be nuclear to keep the lights on, if there has to be, and this is a question the energy review will decide, it can only stand on its own two feet it can't have any special support or any special privileges or subsidies.
"And there's been massive subsidy, around £70bn pounds worth of liabilities from the old nuclear power programme we can never go down that road again because otherwise that would crowd out renewable energy and the future forms of energy that could come on stream in decades to come.
"So if there has to be a new nuclear power station or three or four or whatever it might be that is up to private developers.
"They have to finance it, they have to sort out the decommissioning costs they have to deal with the waste disposal costs and make sure it's safe and then if in order to keeps the lights on people decide there has to be nuclear, I'm sceptical about it.
"But if there has to be, it can only and must only be in a way that doesn't crowd out any renewable development."
Not good enough?
Mr Hain, who is also Welsh secretary, went on to warn there was "too much nimbyism" about renewable energy adding that he was an enthusiast for wind power.
"Not on every Welsh mountaintop, of course not, not off every beach in Wales or Northern Ireland of course not. But there's a massive inbuilt prejudice against anything in your own back yard," he said.
"The other side of this coin is that those who want clean green energy as I do and are sceptical about nuclear as I am if they really want to go for it they've got to be much more supportive about wind farm developments about tidal and offshore developments including marine current and including wave power.
"At the moment everybody says they're opposed to nuclear, everybody says they want clean energy but when it comes to a project near them they say 'no', and that's not good enough."