Fukushima nuclear plant operator TEPCO on Monday slashed its outlook for the fiscal year to March, warning it expected to lose about $1.29 billion or almost three times an earlier estimate.

The embattled utility at the centre of the worst nuclear accident in a generation cited growing compensation and energy expenses for its weaker outlook, with its chief saying the firm would keep trying to cut its costs.

"It is very tough," TEPCO president Naomi Hirose was quoted as telling a Tokyo press briefing. "We must move forward by implementing rationalisation at different levels to cut costs."

The move marked a reversal of its estimate late last year, which saw TEPCO dramatically slash its expected full-year loss to 45 billion yen from 160 billion yen, citing asset sales and cost-cutting for the change.

TEPCO (Tokyo Electric Power) said its fuel costs shot up after Japan shuttered its nuclear reactors in the wake of the 2011 quake-tsunami disaster and subsequent atomic disaster at Fukushima, forcing operators to turn to pricey fossil fuel alternatives.

A slide in the yen over the past few months has made energy imports costlier for Japanese firms, with TEPCO saying Monday its operating costs rose 12.4 percent in the nine months to December from a year earlier.

The rise was "due to an increase in the consumption of fuel for thermal power generation after the total shutdown of nuclear power generation as well as an increase in fuel prices", TEPCO said in a statement.

The company said it was on track to make a net loss of 120 billion yen ($1.29 billion) for the full fiscal year.

It said its net loss in the nine months to December shrank to 2.22 billion yen from a whopping 623.01 billion loss in the same period a year earlier following Japan's natural disasters and atomic crisis.

Sales in the nine-month period rose to 4.33 trillion yen from 3.80 trillion yen, the company said.

Also Monday, Japan's government approved an earlier request from the company to contribute more money to help pay ballooning bills for compensating victims of the crisis. The request was for another 697 billion yen, bringing TEPCO's estimated compensation costs to 3.24 trillion yen.

Aside from compensation costs TEPCO faces a growing bill, estimated at more than 10 trillion yen, for the work to dismantle the crippled Fukushima plant and clean areas polluted by radiation.

A public-private body -- the Nuclear Damage Liability Facilitation Fund, which was created to deal with the disaster -- is providing the aid, which must be repaid by TEPCO in the future.

The company is facing lawsuits while Japanese media have reported that prosecutors questioned TEPCO's former head on suspicion of negligence.

Critics say company executives failed to take measures after TEPCO estimated in 2008 that the plant was vulnerable to a tsunami higher than 15 metres (50 feet), the reports said.

Despite strong anti-nuclear sentiment in Japan, a new conservative government swept to power in December and cast doubt on the previous administration's plan to ditch nuclear power.

Hawkish new Prime Minister Shinzo Abe has derided the zero-nuclear goal as unrealistic and "irresponsible" -- and hinted at keeping atomic power.

A 9.0-magnitude tremor struck off Japan's northeast coast in March 2011, triggering monster waves that swamped the Fukushima plant's cooling systems, sparking reactor meltdowns and radiation leaks.

Tens of thousands of people have been evacuated from around the plant.