Tepco, the operator of Japan's crippled Fukushima nuclear plant, said Friday it booked a whopping $7.54 billion April-December profit owing to an electricity rate hike and its massive government bailout.

Tokyo Electric Power (Tepco) was teetering on the brink as cleanup and compensation costs stoked huge losses and threatened to collapse the sprawling utility until Tokyo stepped with a multi-billion dollar rescue.

The company at the centre of the worst nuclear accident in a generation said it earned 772.9 billion yen ($7.54 billion) in the nine months to December, compared with a net loss of 2.2 billion yen in the same period a year earlier.

Sales rose 10.8 percent to 4.8 trillion yen.

A rate hike helped offset a decline in the amount of electricity Tepco sold owing to warmer-than-usual weather that cut demand for heating.

It also booked a special gain of nearly 1.8 trillion yen based on funds the company received from a government-backed bailout fund.

Pressuring its bottom line, Tepco said it faces rising fuel costs as it relies on fossil fuel-powered thermal plants after all off Japan's nuclear reactors were shut in response to the Fukushima Daiichi alert that was caused by the March 2011 quake-tsunami disaster.

The plant's cooling systems were swamped by monster waves, sparking reactor meltdowns and radiation leaks.

Tens of thousands of people were evacuated from around the plant with decommissioning of the site expected to take decades.