United Democrat legislator Cheung Man-kwong said the figures showed a worrying trend which indicated inmates had a lack of confidence in the internal complaints system provided by the CSD.

Scrutiny by outsiders is mainly conducted by magistrates visiting designated institutions at least once every two weeks and training centres once a month.

They monitor living and working conditions.

Inmates can also lodge complaints to Legco's Complaints Unit, which in turn refers problematic cases to the Office of the Commissioner for Administrative Complaints, or the ombudsman.

In 1992 and 1993, a total of 1,070 magistrate visits were made to various institutions. Almost all visits were conducted within normal office hours.

But some legislators were concerned whether the visits were cosmetic, because the magistrates were accompanied by CSD officials.

Legislators said the low rate of complaints being substantiated might indicate an element of unfairness in the investigations.

Complaints launched by inmates are handled by the Complaints Investigation Unit, which is headed by an assistant commissioner of the CSD and assisted by a senior superintendent.

Of the 1,031 complaints lodged since 1988, a total of 69 were substantiated - a rate of 6.7 per cent.

A Case Review Committee was set up last year to handle appeals by inmates over decisions handed down by the unit. The review committee is also headed by the CSD assistant commissioner.

Legislators queried whether the present system could secure credibility with both inmates and the public since CSD officials were handling the complaints themselves.

The Legco Security Panel will discuss whether outsiders could be introduced to the CSD complaint system.