A man listed as the oldest living male in Tokyo in fact died some 30 years ago, city officials said after his body was found mummified in his bed.

Police visited the home of Sogen Kato at the request of ward officials updating their list of centenarians ahead of Respect for the Elderly Day in September. Kato was born July 22, 1899.

Welfare officials have tried to meet Kato since earlier this year, but his family members repeatedly chased them away, saying Kato was well but didn't want to see anyone, said Tomoko Iwamatsu, an official at Tokyo's downtown Adachi Ward, where Kato lived.

Officials grew suspicious and sought an investigation by police, who forced their way into the house Wednesday. Police said the mummified body believed to be Kato was lying in his bed, wearing underwear and pyjamas, covered with a blanket.

His granddaughter told investigators Kato holed up in his room about 30 years ago after declaring he wanted to be a living Buddha, police and Tokyo officials said. They believe Kato died soon after that.

Tokyo police were investigating possible crimes on suspicion Kato's family received pension money of the man and his dead wife.

"His family must have known he has been dead all these years and acted as if nothing happened," said Tokyo metropolitan welfare official Yutaka Muroi. "It's so eerie."