The Ministry of Justice said the officer, whose name was not released publicly, could face disciplinary action depending on the result of the investigation.

According to the ministry on Sunday, the Seoul Regional Correctional Headquarters is investigating allegations that the officer asked Kim for money in September, saying: “I helped you get into Somang Correctional Institution.”

Kim rejected the request and reported the incident to another prison officer, the ministry said.

The trot singer, who was sentenced to two years and six months in prison for a hit-and-run drink-driving incident in Seoul’s Gangnam district last May, was initially held at the Seoul Detention Centre before being transferred to the Somang Correctional Institution in August.

He was found guilty of causing the accident and having his manager turn himself in on his behalf.