A report has accused the Japanese government of forcing evacuees to return to areas with radioactive contamination at higher levels than internationally recommended safe levels.
A Greenpeace report has said that of the 160,000 who fled their homes in the Fukushima area which was devastated when a tsunami damaged a nuclear power plant causing it to leak radioactive material, 80,000 have not yet returned.
"Many may be forced to return to contaminated communities against their wishes because they cannot afford to stay where they are currently living.
"This is economic coercion, not a choice freely made," the report reads.
Greenpeace issued a statement saying that the Japanese government's response to the nuclear disaster "resulted in multiple human rights violations, particularly for women and children".
Residents who do not return to homes that are not in mandatory exclusion zones could risk losing their housing benefits.
By the end of March, Japan is set to lift evacuation orders for parts of Namie, situated only 2.5 miles from the nuclear plant, as well as three other towns.
The six-year anniversary of the Fukushima disaster, which claimed the lives of around 18,500 people, was marked in Japan on Saturday (11 March).
Prime Minister Shinzō Abe addressed a national ceremony in Tokyo and bowed his head in silence at 2.46pm local time.
"When I think of the despair of those who lost beloved members of their families and friends in the disaster, I am overwhelmed even now with deep sorrow," he told the assembled crowd.
Prince Akishino was also in attendance, in place of his father Emperor Akihito and mother Empress Michiko, and offered his condolences to the dead.
"My heart aches deeply," Akishino said.
Several hundred demonstrators gathered near Abe's office and in front of parliament to denounce government policy to restart nuclear reactors around the country shuttered after the disaster.
"Learn from Fukushima!" and "Fukushima is angry!" read protest banners.
The 9 magnitude quake struck Japan in 2011 and left more than 100,000 people homeless, and causing the worst nuclear disaster since Chernobyl in 1986.
In 2016 the government estimated total costs from the nuclear disaster at about ¥22tn (£155bn) according to LiveScience.
Work on the site of the nuclear disaster has been slow, particularly dealing with radioactive water, which reached 1.02 million tonnes in March, according to Japan News.