He also rejected the idea of offering government subsidies to developers of new nuclear plants.

"I think the sensible precaution is to have a balanced energy policy. You put it all in the mix," Blair said.

"To take out of that nuclear power ... is a very, very big step for us to take and I would need a lot of convincing that renewables are going to fill the gap," he told a reception of magazine editors at his Downing Street office.

Blair's government is expected to announce the findings of an energy policy review next month.

But Blair in May said the replacement of Britain's ageing nuclear plants was "back on the agenda with a vengeance", angering environmentalists who said it showed he had already decided to back nuclear power before the review was complete.

The government argues that a mix of energy sources is essential to prevent the country from becoming dependent on power from Russia and the Middle East.

"There are people who say you can make it all up through renewables, but if they are wrong, in 15 or 20 years, we are going to have a serious problem in this country, and we will be completely dependent on imports of oil and gas from abroad," Blair said. "My view is that's a dangerous gamble to take."

Asked if taxpayers would be asked to subsidise private companies that build new power plants, Blair said: "We are not in the business of subsidies. We are in the business, however, of permission, if that's the way people want to go."