Seventeen human rights and citizens' groups submitted a petition to the Justice Ministry on Wednesday slamming its proposal to reform criminal investigations as "far from enough" to improve transparency and prevent wrongful arrests.

The proposal, outlined by the ministry on April 30, laid the groundwork for a report, due to be released soon, on how to improve Japan's long-criticized criminal justice system.

The April proposal offered two options on how much to expand the range of criminal interrogations, subject to full electronic recording. The petition submitted Wednesday states that neither would lead to real reform.

The first option would mandate video recording of interrogations conducted by both police investigators and prosecutors, but only for cases that will be deliberated by lay judges, such as murder and arson. Critics point out these "grave" cases account only for 3 percent of all criminal cases.

The second option would require full video recording of interrogations regarding all criminal cases, but only when they are led by prosecutors, not police investigators.

Yuichi Kaido, head of the nonprofit organization Center for Prisoners' Rights, said neither option goes far enough to remove the possibility of erroneous criminal convictions.

"We believe full video recording must be applied to interrogations led by both the police and prosecutors in all criminal cases" if the ministry is really serious about preventing injustices, Kaido said.

He also slammed the proposal for ignoring the "horrific realities" surrounding the "daiyo kangoku" substitute detention cells inside police stations, which critics say lead to false convictions.

These cells are used by police to subject suspects to constant surveillance for as long as 23 days. According to the "global standard" police detention is generally limited to three days, Kaido said.