Tony Blair says "controversial and difficult" decisions will have to be taken over the need for nuclear power to tackle the UK energy crisis.
Can nuclear power help against climate change?
The prime minister told the Liaison Committee, made up of the 31 MPs who chair Commons committees, any decision will be taken in the national interest.
He is said to believe nuclear power can improve the security of the UK's energy supply and also help on climate change.
A government review of energy options is expected to be announced next week.
Other subjects covered include:
- Mr Blair defended his decision not to allow the ex-BBC director general Lord Birt, employed as a "blue skies thinker" in Number 10, to be grilled by MPs. Mr Blair said he felt Stephen Aldridge, acting head of the Downing Street Strategy Unit, was "best placed" to answer MPs' questions.
- Mr Blair was asked if he was "in a hurry" to complete his health and education reforms before he left office. Mr Blair defended his plans and said he hoped the "basic elements" of reform would be in place by the time he stepped down. He did not regret abolishing grant maintained schools in 1997, which had "unfair admissions and unfair funding".
- The government's record on promoting equality between ethnic communities was as good as any in Europe, said Mr Blair.
- He accepted that legislation to grant an amnesty to Northern Ireland terrorists on the run would cause "anger and anguish", but said it was needed to give momentum to the stalled peace process.
- Computer projects in government were "always difficult", he said, but said the NHS and criminal justice system were areas where IT "can deliver huge savings".
- Mr Blair said it was "rubbish" for one of the 7 July London bombers to suggest that his grievance against the UK was that it was oppressing Muslims.
- Mr Blair said terrorism would be defeated if Iraq and Afghanistan became stable democracies. But he said he had been "too optimistic" about the eradication of the heroin trade in Afghanistan. He could not be sure of the exact numbers of civilians killed in Iraq.
- Mr Blair said if Iran was to develop a nuclear weapons capability it would be a "very serious threat to world stability". He was also concerned about Iran's support for terrorism in the Middle East and its "meddling in Iraq".
- Mr Blair said he had made it clear that Guantanamo Bay was "an anomaly that sooner or later has to be dealt with".
The two and a half hour session in a House of Commons committee room began with questions about whether he would be prepared to take unpopular decisions on issues such as climate change and nuclear power.
Mr Blair 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 conceded that there were strongly held positions on issues such as nuclear power.
"About energy security and supply that will mean issues that are bound to be extremely controversial," he said.
But he insisted that the reason why people were coming round to the nuclear option was "because the facts have changed".