AREPORT to be released today recommends that an independent body outside the police should be responsible for monitoring an amnesty scheme to make sure young offenders receive fair treatment. The report, of which Young Post had a preview, revealed a number of shortcomings in the present procedures relating to young offenders, such as language barriers and admission of guilt before a proper investigation is carried out (see story below). The report, ''Decriminalising Juvenile Offences: Police Superintendents' Discretion Scheme and Follow-up Services'', is the first detailed survey of its kind. It was researched and compiled by the Hong Kong Federation of Youth Groups. The Police Superintendents' Discretion Scheme (PSDS), begun in 1963, aims to give first offenders below 17 charged with minor crimes a chance to avoid getting a criminal record. Under the scheme, young offenders are cautioned by the police and discharged. Home visits and other follow-up work are part of the rehabilitation programme. Last year, over 2,500 young offenders between seven and 16 years, charged with crimes ranging from assault and robbery to blackmail and shoplifting, were discharged under the scheme. The survey team spoke to 21 young people who came under the PSDS (the cases were referred by various social agencies with the consent of the clients). Several concerned parties were also interviewed, including representatives from the police, the JPS and officers of the Correctional Service Section of the Social Welfare Department. The Hong Kong Federation of Youth Groups recommends the setting up of an independent group outside the police force to monitor the scheme. The federation calls for details of the PSDS operation and regular reports on statistics, including figures for unconditional discharge, which are not presently available. ''We suggested the community monitoring be performed by the Central and District Fight Crime Committees which will be able to reflect opinions of various sectors of the community,'' the federation added. It also recommended setting up a legally trained social work team to bridge the gap between various social service branches and to help clients who need professional and legal advice. ''Their instant intervention at the beginning of the case investigation would provide offenders with independent information about the consequences of the offence and any courses of action possible,'' the report said. ''They would be able to intervene in crises arising from unsatisfactory social relationships and emotional problems,'' said the report. But the report said help would be given on a voluntary basis, with respect to the wishes of the clients and their families. The police, however, must inform the client of the available services and make arrangements for such services, the report stressed. ''The PSDS provides an opportunity for young offenders to rehabilitate themselves,'' the federation concluded. ''It should be extended in an effort to provide further rehabilitation opportunities.''