Juvenile crimes are getting more heinous and are increasingly committed by groups rather than individuals, according to a midterm report on youth crimes released Tuesday by the Justice Ministry.

The report also says that, out of cases of murder and attempted murder by youths tried in criminal courts over the last 10 years, 83 percent involved the use of weapons, including knives, and 61 percent were committed by groups.

The ministry compiled the report for use in discussions on whether the age at which youths can be tried in criminals courts should be lowered from the current 16 to 14. The ministry has been compiling the data since March from its criminal affairs, rehabilitation and correction bureaus as well as through an in-house research institute.

Under the Penal Code, people age 14 and older can be held responsible for crimes, but the Juvenile Law holds that only those age 16 and older can be tried in criminal courts. Public calls for eliminating the discrepancy between the two laws have mounted since the May 1997 slaying and beheading of an 11-year-old Kobe boy by a 14-year-old boy, whose case was sent to a family court instead of a criminal court.

Justice Minister Kokichi Shimoinaba told a regular news conference that the age issue warrants further review, although the report per se does not suggest an increase in crimes by 14- and 15-year-olds.