After challenges from environmentalists concerned about nuclear safety, the government has launched a nationwide public consultation on atomic energy, while trying to come up with an alternative "plan B" if it changes its mind.

"It isn't inconceivable that the government might reverse its view and therefore we would need to come up with some proposals ... about what the alternative strategies might be if nuclear should be rejected," a spokeswoman for the Department for Business, Enterprise and Regulatory Reform said.

"Civil servants are doing preparatory work on the alternative solutions."

She said it was still too early to say what sources of energy might be used to plug the gap left by nuclear power's possible demise.

Nuclear power currently supplies just under a fifth of Britain's electricity, but all but one of its nuclear power plants are expected to close by 2020.

The government has already ruled out building or giving financial support to new nuclear power stations and said that if the private sector does not do it, then there will not be any nuclear power in Britain.

The government admitted last week that Britain's current target of getting 20 percent of its power from renewable sources of energy by 2020 is already very challenging.