Tokyo Electric Power Company (Tepco), owner of the crippled Fukushima Daiichi nuclear plant, has been sued by eight US sailors over radiation exposure. They claim that Tepco lied about the threat posed by the leaks after the March 2011 earthquake and tsunami damaged the plant.
The sailors were involved in relief operations after the natural disasters.
They have each sought $10m (£6m) in compensatory damages and $30m in punitive damages from Tepco.
The eight, who have filed the case in a US Federal Court in San Diego, also want Tepco to set up a $100m fund to pay for their medical expenses.
They have claimed that the utility provider created an impression that the level of radiation leaks from the nuclear plant did not pose any threat.
As a result, the sailors say they went to areas that were unsafe and were exposed to radiation.
When contacted by the BBC, Tepco acknowledged that it has been sued, but said that it had not received the actual complaint and so was not in a position to comment.
The lawsuit is the latest setback for Tepco which is already facing billions of dollars in compensation claims.
The radiation leaks resulted in thousands of people and businesses being evacuated from the areas surrounding the plant.
On Thursday, the firm said that it now expects the compensation costs to total at 3.24 trillion yen ($38bn; £23bn), up 697 billion yen from its earlier projection.
The firm has already received nearly 1tn yen in government aid.
The utility was, in effect, nationalised after the government took a 50.11% stake in the group in exchange for the capital injection.