TOKYO - The suicide of an Indian man being held at an immigration detention center in Japan has sparked a hunger strike among detainees and revived concerns about conditions.

Deepak Kumar was found dead on April 13 after apparently hanging himself in the shower at the Ushiku facility, northeast of Tokyo.

At least eight detainees, including Kumar, have died in immigration detention facilities since 2010, according to a tally by the Japan Association for Refugees.

Kumar's death prompted a hunger strike, with around 70 people at the Ushiku facility refusing food by Friday, according to an official, and reports that people held at other centers were also protesting.

Around 1,000 people are held in immigration detention centers around Japan, according to JAR, and there have long been concerns about conditions, with a series of deaths raising questions about medical access and oversight.

Last year, a Vietnamese man died in the Ushiku facility after having a stroke, and in 2014 two detainees, an Iranian and a Cameroonian, died there.

"One death in ten years is too much," said Eri Ishikawa, chair of JAR's board.

"But in reality, in these three to five years, every year there has been an incidence of death among detainees."

Authorities deny that detainees are being mistreated or neglected.

"We respect their human rights," said Daisuke Akinaga, an official at the Ushiku facility. "We try to listen to them and meet their requests. For example, there was a complaint about cold inside the facility and we improved the situation."

Kumar's brother Sanju said the family was devastated, and was calling for an investigation.

"There was no reason for him to commit suicide, he was a courageous man and had a fighting spirit," he said from Ludhiana, in India's Punjab state.

Activists and rights group have long urged reforms and also criticize the government's rules on granting refugee status. Last year just 20 people out of nearly 20,000 applicants received asylum.

Agence France-presse