Authorities are investigating the death of a Sri Lankan man at an immigration detention center in Tokyo, the fourth such case in just over a year, amid criticism the facilities are overcrowded and understaffed.

Tokyo's Immigration Office confirmed that a Sri Lankan man died in detention, but refused to identify him, citing an ongoing investigation.

Mitsuru Miyasako of the Provisional Release Association in Japan, a group representing refugees and immigrants, said Nickeles Fernando, 57, died at the Shinagawa Immigration Center last month after complaining of chest pains.

Miyasako, who is in contact with the man's family, said he was advised the Sri Lankan had requested emergency medical help, but was denied it.

Sachiko Asai from the Tokyo Immigration Office said that staff carried out first aid and called an ambulance. The man was later confirmed dead in a hospital.

"The responsibility for the well-being of the detainees lies in the hands of those who detain," said Kanae Doi from Human Rights Watch in Tokyo. "This incident should be investigated and those responsibile held accountable for what happened."

Last month the Justice Ministry found a detention center in Ibaraki Prefecture had inadequate medical care after an investigation sparked by the deaths of a Cameroonian man and an Iranian man in separate incidents in March.

Japan, which imposes strict immigration policies, detained 15,000 people in 2013, according to Justice Ministry data.

Lawyers and human rights advocates say Japan's immigration centers are outdated and understaffed. The Shinagawa facility, where the Sri Lankan national was held, can hold up to 800 detainees.

A Rohingya detainee died of a brain haemorrhage at the Shinagawa facility in October last year.