The Cabinet approved a bill Friday to improve the treatment of criminal suspects before trial or defendants awaiting sentencing while in police custody.

The bill contains a provision that maintains the controversial police detention facilities known in Japanese as "daiyo kangoku," which are used to hold detainees prior to indictment. This substitute prison system has drawn criticism at home and abroad for fostering human rights abuses.

The bill calls for clearly separating police officers in charge of investigations from those who supervise detainees to ensure fairer treatment, the officials said. The government will submit the bill to the ongoing Diet session. The treatment of pretrial or presentencing detainees is currently governed by the century-old Prison Law.

Because the law is often ambiguous on the rights and obligation of detainees in police custody, the Japan Federation of Bar Associations has criticized it for creating a "hotbed of forced confessions and false accusations."

The bill would require police supervising lockups to sufficiently consider the detainees' rights because their legal status differs from that of actual prison convicts.

To improve these facilities, the bill prohibits supervising officers from engaging in investigative activities related to detainees.

It calls for creating a committee made up of members of the public, lawyers and third parties at police headquarters nationwide so detainees can communicate their opinions regarding the treatment by police through interviews.