The UN atomic agency predicted Friday continued growth in nuclear power in the coming 15 years but trimmed its projections because of low fossil fuel prices and competition from renewables.

"Nuclear energy, in the long run, will continue to play an important role in the world's energy mix," the International Atomic Energy Agency said in a new report.

The low end of its forecast sees worldwide nuclear power generating capacity expanding 1.9 percent by 2030 to 390.2 gigawatts (GW) -- a gigawatt is one billion watts of electrical power -- from 2015.

The upper end foresees an expansion of 56 percent to 598.2 GW. Previously the IAEA's projections were higher, estimating growth of between 2.4 percent and 68 percent.

The low case assumes a continuation of current market, technology and resource trends with few changes to policies affecting nuclear power, the IAEA said.

The high case assumes current rates of economic and electricity demand growth, particularly in Asia, plus countries turning more to nuclear to meet their commitments under the 2015 Paris Agreement on climate change.