TOKYO (REUTERS) - Japan may face a total nuclear shutdown in the summer for the second time since the March 2011 Fukushima disaster as the country's two operating reactors close for maintenance and tough new safety checks keep the rest of the fleet offline.

That could force Japan to import even more fossil fuels for power generation, adding to an onerous energy bill that helped push the country into a record trade deficit in 2012.

"It is unlikely that any of the idled reactors will re-start prior to September due to ongoing investigations of seismic issues at certain plants and due to the fact that safety standards have still not been finalised by the Nuclear Regulation Authority," said Mr Tom O'Sullivan, a Tokyo-based energy consultant.

"Local approvals will also be necessary for restarts, adding a further layer of complication," he said.

The previous Democratic Party of Japan government's decision last June to restart two reactors weeks after the last full shutdown galvanized the country's previously dormant anti-nuclear movement, sparking the biggest demonstrations in decades and contributing to its downfall in elections in December.

Media surveys have shown a majority of Japanese want to abandon atomic energy by 2030, if not sooner, making the decision to restart even reactors deemed safe a risky proposition for the new Liberal Democratic Party government.

Utilities and the government, however, are keen to reduce expensive oil and gas imports. Japan is already the world's top liquefied natural gas (LNG) importer, and volumes rose 11.2 per cent to a record 87.31 million tonnes in 2012 from a year earlier, according to government data. That is more than one third of global trade of about 240 million tonnes in LNG in 2011.

Crude oil imports rose 2 per cent in 2012 to 3.66 million barrels a day, from a 22-year low in 2011. Thermal coal imports were up 6.5 per cent to 107.7 million tonnes.