A man who helped clean up a Japanese nuclear plant after it was hit by a tsunami has died due to the radiation.

It is the first time the government has acknowledged a connection between a death and radiation exposure at the Fukushima plant, according to Japanese news reports.

In March 2011, a massive magnitude nine earthquake shook the country's north east, triggering a tsunami that caused the plant's meltdown.

The man in his 50s was in charge of measuring radiation at the plant after the disaster and he worked there until December, 2011.

He also worked at other atomic power stations across Japan between 1980 and 2015 and is said to have worn a full-face mask and protective suit, Japan's Ministry of Health, Labour and Welfare said.

In February 2016, he was diagnosed with lung cancer.

The man was not publicly identified and his family asked that the exact date of his death remain private.

In this November 2011 photo, street lights shine in the abandoned town of Iitate | Image: Greg Baker/AP/Press Association Images

The Japanese government has already paid compensation in the cases of four workers who developed cancer, according to reports.

A Japanese daily newspaper, Asahi Shimbun, says 17 plant workers have filed for compensation.

Along with the four who had their claims accepted, five claims have been rejected.

Another five are pending, and two have been withdrawn.

The tsunami killed around 18,000 people and caused a failure in the nuclear plant's cooling system, resulting in a level seven meltdown and the release of radioactive materials.

The nuclear disaster was the worst since Chernobyl and forced tens of thousands of people to flee their homes.

The area near the plant remains uninhabitable due to the danger from radiation.