Wearing a protective suit and a mask, an employee of Japan's Tokyo Electric Power Co. (TEPCO) walks carefully along a dark aisle after U.S. Ambassador to Japan Caroline Kennedy visited the central control room for the unit one and unit two reactors at TEP
Wearing a protective suit and a mask, an employee of Japan's Tokyo Electric Power Co. (TEPCO) walks carefully along a dark aisle after U.S. Ambassador to Japan Caroline Kennedy visited the central control room for the unit one and unit two reactors at TEPCO's tsunami-crippled Fukushima Daiichi nuclear plant at Okuma town in Fukushima prefecture May 14, 2014. REUTERS/Toru Yamanaka/Pool Reuters/Toru Yamanaka/Pool

Workers tasked to decommission the highly radiated Fukushima Daiichi nuclear power plant have slapped a lawsuit against operator Tokyo Electric Company (Tepco) over unpaid hazard wages.

The complainants who are four men, two of whom are still working at the plant, are demanding a total of 65 million yen ($620,000), mostly in hazard allowances from Tepco.

They stated in their complaint that the compensation they are currently receiving for removing contaminated debris and patrolling the plant is inadequate given the risks involved to their health and overall well-being.

The complainants' ages range from 30s to 60s.

The suit was filed on Wednesday with the Iwaki branch of the Fukushima District Court, Tsuguo Hirota, the complainants' lawyer, said. The workers wore masks to court when they filed the lawsuit.

"My health may be harmed some day... I believe there are many people who can't speak out about this kind of (underpaying) problem," one of the workers told public broadcaster NHK.

"I may get fired or may be given no further work. But I hope people will take this as an opportunity to speak up and get paid," he said.

This is the first time that Tepco has been slapped with a lawsuit by workers who are still employed at the plant. Various reports before have earlier flaunted of widespread exploitation and abuses to the workers.

If they win, their victory will surely set a precedent to other workers to come forward and demand just compensation from the company.

Tepco had been struggling to contain the contaminated water problem around the facility since it got hit by a massive earthquake and tsunami in March 2011. The plant reactors' cooling systems were knocked out, leading to meltdowns and the release of radioactive material.

There are currently 6,000 people working at the plant daily over the last two months involved in the clean-up and decommissioning work at Fukushima. But only a few are directly employed by Tepco. The company has opted to use several layers of contractors and subcontractors.

According to Asahi Shimbun, Tepco doubled the allowance a plant worker receives to 20,000 yen a day per person starting December 2013. The four men, however, said they have never received any hazard payment since they started working at the plant.