The government faces a "major decision" on whether to approve a new generation of nuclear power stations, Prime Minister Gordon Brown has told MPs.
The Cabinet has backed plans for more nuclear power stations
He said ministers were also looking at possibilities including the greater use of more renewable energy sources.
Speaking during prime minister's questions, he said the UK would become more "independent" of other countries in supplying its own power.
The government is due to outline its policy on nuclear energy on Thursday.
Mr Brown said: "We face a major decision in this country about the future of energy.
"Tomorrow the secretary of state for business, enterprise and regulatory reform will make a decision on energy and nuclear power.
"Whatever the decision on this and renewable fuels, we will become more independent [from needing to buy energy from abroad]."
This would "protect the long term interests of the country".
He added: "It's quite a shock to me that other parties are leaning in different directions."
The Cabinet has agreed in principle to approve a new generation of nuclear power stations.
Environmental campaigners say such a move will be expensive and dangerous. Greenpeace says atomic power will not meet the projected energy shortfall.
But Mr Brown has said the decision is "a fundamental precondition of preparing Britain for the new world".
His predecessor as prime minister, Tony Blair, said in 2006 that the government believed new nuclear stations should be built.
But that decision was put on hold after the consultation element of the initial energy review was ruled "seriously flawed" and "misleading" by a High Court judge, following a challenge by Greenpeace.