Nuclear energy remains vital to cope with rising energy demand, mainly in emerging economies, fight global warming and avert increased damage to the environment, the IEA warned on Wednesday.

The IEA also warned that global nuclear generation capacity could fall by 15.0 percent by 2035 if countries such as Germany and Belgium pressed ahead with cutting their nuclear output in the light of the nuclear accident at Fukushima in Japan in April.

A pullback from nuclear production, amid a rise in demand for energy, was likely to drive countries towards increased use of coal and gas, and therefore to generating extra carbon pollution with a devastating effect on the environment.

The energy independence of nuclear-power producing countries would also be in danger because their sources of supply would be reduced, the International Energy Agency said.

And the price of non-nuclear sources of energy would rise sharply, the IEA said, forecasting that in any case global oil demand was set to grow by 14.0 percent by 2035, pulled by China and emerging economies.

Oil prices could rise to 120 dollars per barrel, the IEA said in its annual report and it warned that the world had to change the way it was consuming energy.

"Without a bold change of policy direction, the world will lock itself into an insecure, inefficient and high-carbon energy system," IEA executive director Maria van der Hoeven said in the 24-page report.

"Growth, prosperity and rising population will inevitably push up energy needs over the coming decades."

"But we cannot continue to rely on insecure and environmentally unsustainable use of energy," Van der Hoeven added.

The agency estimated in its World Energy Outlook publication that global demand for oil would total 99 million barrels per day in 2035, or 12 mbd more than in 2010, and said that the price could reach $120 per barrel despite current price volatility.

Van der Hoeven said: "The Fukushima nuclear accident, the turmoil in parts of the Middle East and North Africa and a sharp rebound in energy demand in 2010 which pushed CO2 (carbon) emissions to a record high, highlight the urgency and scale of the challenge."

The IEA said that under its central outlook "scenario", assuming that governments applied their recent commitments in a "cautious manner", then what it termed "primary energy demand" would increase by one third between 2010 and 2035, with 90 percent of the growth being generated outside the area covered by the Organisation for Economic Cooperation and Development.

The IEA is the energy policy and research arm of the OECD which acts as a policy forum, and manages strategic stockpiles, for advanced economies.

The emergence of China as the "world's largest energy consumer" would be consolidated, and China would use 70 percent more energy that the United States by 2035.

But even then, each Chinese person would be consuming less than half the amount of energy used annually by each person in the United States.

On the basis that governments implemented policy changes which they have promised, the percentage of primary energy generated from fossil fuels would fall to 75 percent of the total from 81 percent now.

The proportion of energy generated from renewable sources would increase from 13 percent to 18 percent by 2035, the report said.

In the short term, pressure on the oil markets were easing, the report said, with the expected return of the Libyan supply following the fall of Moamer Kadhafi's regime last month.

Longer term towards 2035, reliance on a small number of oil producers will increase with a need for output by Middle Eastern and North African producers to grow to account for more than 90 percent in global oil output.

The IEA said that the global fleet of passenger vehicles would double to 1.7 billion cars.

The use of coal, which the IAE said accounted for almost half the use of energy around the world in the last decade, would rise by 65 percent by 2035.

More efficient power plants and carbon capture and storage technology (CSS) "could boost prospects for coal", although CSS still faced "significant regulatory, policy and technical barriers that make its deployment uncertain," the report said.

The future of natural gas was more certain with its use catching up to that of coal consumption.

The IEA pointed out that Russia particularly stood to benefit from an increased demand in gas, but Moscow's key challenges remained financing a new generation of oil and gas fields and and improve its energy efficiency.

"Cumulative carbon dioxide emissions over the last 25 years amounted to three-quarters of the total output from the past 110 years leading to a long-term average temperature side of 3.5 degrees Celsius," the report said.

"Were new policies not implemented, we are on an even more dangerous track, to an increase of 6 degrees," it warned.