Japanese utility Tokyo Electric Power was expected to report a net loss of at least $2.56 billion for the April-June quarter due to costs from the Fukushima nuclear disaster, media said Wednesday.
Losses were also heightened by the surging cost of fossil fuels to run obsolete conventional power plants while nuclear reactors are offline due to public opposition, according to major newspapers including the Nikkei.
The net loss was seen as being at least 200 billion yen ($2.56 billion), and may have reached around 250 billion yen, the Nikkei said.
TEPCO was likely to book extraordinary losses of more than 100 billion yen to pay compensation claims from victims of the Fukushima disaster, the business daily said.
The operating loss for the quarter was seen at around 100 billion yen, said the Asahi Shimbun, the Nikkei and other media.
Japan was plunged into the world's worst nuclear crisis since Chernobyl after TEPCO's Fukushima Daiichi nuclear plant was hit by a killer tsunami triggered by a huge earthquake on March 11, 2011.
The power station went through meltdowns and explosions, contaminating vast swathes of farmland and forcing tens of thousands of people from their homes.
The clean-up is expected to take decades, with scientists warning that some settlements may have to be abandoned.
The company was expected to officially announce its quarterly earnings results later in the day, local media said.
The firm's spokesman told AFP that it had yet to decide when to announce the figures.
The media reports came after TEPCO was effectively taken under state control, having received $12.8 billion of taxpayer money to stay afloat.
The company is also preparing to raise power bills.