Notorious for a lack of transparency over how suspects are interrogated in criminal investigations, Japan has been under pressure to record its cross-questioning of detainees behind closed doors.

But at least 97 percent of criminal interrogations will continue to go unrecorded, after an advisory panel of bureaucrats, legal experts, professors and others under the Justice Ministry's Legislative Council on Monday supported a draft compiled by the ministry that stops short of requiring investigators to keep detailed records in most cases.

Meanwhile, Japan is set to broaden the range of methods police and prosecutors can use by introducing plea bargaining and expanding the use of the wiretap law, something that investigators are eyeing eagerly as a new tool in securing prosecutions.