The government released an annual energy report Tuesday that called for a return to nuclear power generation, saying increasing fuel costs for thermal power and a surge in CO2 emissions are reasons why Japan should power up its idled reactors.

The report reflects the pro-nuclear government's latest national energy policy, which defined nuclear power as an "important base-load power source."

All reactors nationwide are currently offline, as most of them have remained since the disaster at the Fukushima No. 1 plant, triggered by the massive earthquake and tsunami of March 2011.

The report says 88 percent of Japan's energy consumption depended on fossil fuels in fiscal 2013, higher than the 80 percent at the time of the oil crisis in the 1970s.

Imports of fuels such as liquefied natural gas rose ¥10 trillion from 2010 to ¥27 trillion in 2013, mainly because thermal power plants have been operating flat out to replace lost nuclear capacity.

"Increasing imports of fossil fuels is seen as a problem not only on the energy front but also in the economic arena," the report said.

The report also noted that CO2 emissions by utilities surged 112 million tons to 486 million tons in fiscal 2012 from fiscal 2010, which could "raise a question about our nation's stance, after taking a leadership role in international efforts against global warming."

Japan plans to "resume operations of nuclear plants" that have satisfied what the government calls "the world's toughest" regulatory standards, introduced following the Fukushima accident, under the premise that safety is the top priority.

In the Basic Energy Plan, adopted by the government of Prime Minister Shinzo Abe in April, the government overturned a nuclear phase-out goal introduced by the previous government, led by the Democratic Party of Japan.