Tony Blair today indicated publicly for the first time that he will support building new nuclear power plants to meet Britain’s future energy needs.

The Prime Minister told MPs that there was fresh impetus to build a new generation of reactors because “the facts have changed over the last couple of years”.

Under questioning from the Commons liaison committee, Mr Blair accepted that Britain faced “difficult and controversial decisions” over climate change and energy supply.

He said that he would not flinch from doing what he believed was right for the long-term future of the country – a statement interpreted as meaning that he would back the use of nuclear power, highly unpopular with sections of his own party.

Asked whether he would be prepared to take hard decisions on issues such as climate change and nuclear power, he replied: “With some of the issues to do with climate change, and you can see it with the debate about nuclear power, there are going to be difficult and controversial decisions Government has got to take.

“And in the end it has got to do what it believes to be right in the long-term interests of the country.”

He said there were strongly held positions on issues such as nuclear power and continued: “About energy security and supply that will mean issues that are bound to be extremely controversial.”

While nuclear reactors do not directly emit greenhouse gases, green campaigners have rejected a new generation of the plants as a viable solution to meeting Britain’s energy needs without contributing to climate change. They said the Government should instead concentrate on promoting renewable power and energy efficiency.

“It is clear that there is a very strong agenda in various forms of government to bring forward the nuclear option, since the time of the election,” he told the Commons Environmental Audit Committee, which is conducting an inquiry into nuclear power and climate change.

Tony Juniper, director of Friends of the Earth, said that Tony Blair and his advisers were exaggerating the importance of nuclear power in fighting climate change. “Nuclear power is not the answer to tackling climate change,” he said. “It is expensive and leaves a legacy that remains dangerous for tens of thousands of years.”

The cross-party panel of 31 MPs questioned Mr Blair on a host of issues central to his leadership during his twice-yearly appearance before the House of Commons Liaison Committee. He made a robust defence of the government’s proposed anti-terror laws, and said that he was optimistic about the future of Iraq and the Middle East.

“In the long term the prospects are good rather than bad,” he said. “Overall it is a healthy progress because the people have had a taste of democracy and liked it.”

Mr Blair joined in the laughter when he was asked if he had thought of copying Ariel Sharon and ditching his political party in order to form a new centrist coalition. He also brushed aside a question about his diminishing popularity: “Whenever you take these decisions you cause a certain amount of turbulence and difficulty, but the important thing, if you know you are doing the right thing, is to carry on doing it.”