Russia and the US have spearheaded a call for increased nuclear power to provide a more secure energy supply for the world.
Energy ministers said fossil fuels would remain the key source
The US called for "substantial rebirth" of nuclear power after a meeting of energy ministers of the powerful Group of Eight (G8) nations in Moscow.
A joint G8 statement said it was vital "for those countries that wish it".
Green groups said nuclear fuel would fail to provide a sustainable energy future or prevent climate change.
US Energy Secretary Samuel Bodman said after the meeting: "We are hopeful of a very substantial rebirth of the global nuclear industry."
A joint statement released by G8 ministers said: "For those countries that wish, wide-scale development of safe and secure nuclear energy is crucial for long-term, environmentally sustainable diversification of energy supply."
Analysts said the difference in tenor of the statements reflected the strong support for nuclear fuel in the US and Russia compared to some other nations such as Germany and Japan.
Andris Pielbalgs, EU commissioner for energy, said: "A common position on nuclear is still difficult to reach because it's still controversial."
Environmentalists strongly oppose the agenda of Moscow and Washington.
Shaun Burnie of Greenpeace International told the Reuters news agency: "The nuclear industry is desperate to secure funding of billions from the taxpayers of the G8.
"If they succeed we will fail in securing a sustainable energy future and will fail to prevent dangerous climate change."
The ministers in Moscow admitted fossil fuels would "remain the basis of the world energy industry for at least the first half of the 21st century".
They called for increased investment in energy along with "stable and predictable regulations, clear tax laws and efficient administration procedures".
Russia's Energy Minister Viktor Khristenko said $17 trillion needed to be invested before 2030 to resist energy shocks and guarantee future supply.
The issue of energy security recently hit headlines when Russia reduced gas supplies flowing towards Western Europe during a dispute with Ukraine.