Japanese immigration authorities said Tuesday a Nigerian man who died in detention in June starved to death while on hunger strike, in the first officially acknowledged case of its kind.
"An autopsy has found the man died of starvation," an official at the Immigration Services Agency told AFP.
The man in his forties, whose name has been withheld, died on June 24 after falling unconscious at Omura Immigration Center and being taken to a hospital in southern Japan.
He had been on a hunger strike for at least three weeks to protest being detained by immigration authorities for over three years, lawyers said.
It was the 14th death in Japanese immigration detention facilities since 2007, according to the Japan Federation of Bar Associations.
The man lost more than 13 kilogrammes (28.7 pounds) over the approximately three weeks since officials noticed he was on a hunger strike, the immigration agency said.
He entered Japan in 2000 and was convicted of crimes including theft, the agency said.
He was released from jail on parole in 2015 but was moved to a detention facility in western Japan's Osaka where he received an extradition order, it added.
The man had been detained at the Omura centre since 2016.
"The situation surrounding detention has been deteriorating," the Japan Federation of Bar Associations said in a statement in August, urging authorities to investigate the death.
After the Nigerian man's death, immigration authorities began releasing detainees on long-term hunger strikes and then re-arresting them two weeks later, the group said.
The agency separately said nearly 200 foreigners held at immigration facilities across the nation refused food during about four months to late September, and 36 of them kept up with the hunger strike as of September 25.
Rights campaigners have criticised the practise as an inhumane attempt to show other detainees that their protests will not result in permanent release.
Human rights campaigners have long criticised conditions at Japanese detention centres, including how guards respond to medical emergencies.
Japan admits very few refugees and asylum seekers, placing a significant burden of proof on those who seek refuge and often detaining migrants for lengthy periods while their cases are processed.