Nippon Cultural Broadcasting Inc. will air an audio recording of an execution carried out at the Osaka Detention House in 1955, a spokesman for the AM radio station said Wednesday.

The controversial broadcast, scheduled for May 6, will be the first-ever by a Japanese radio station, according to NCBI public relations supervisor Katsuhiko Shimizu.

The Justice Ministry is known for its secrecy regarding executions and had refused to release even the names of inmates who were executed until last December. The origin of the tape and its authenticity could not be confirmed.