The 12 former juvenile prisoners were first detained at Her Majesty's pleasure and then at the chief executive's discretion. Some previously had minimum sentences fixed by Tung Chee-hwa, but this was deemed unlawful when the Court of First Instance ruled in September 2002 that the power should rest with the judiciary.

New legislation under the Criminal Procedure (Amendment) Ordinance also came into effect on July 16 this year, giving the secretary for justice six months to apply to the court for the setting of minimum sentences for offenders serving indefinite sentences. The ordinance also empowers a judge to set a minimum sentence or change an indefinite sentence to a fixed-term for murderers convicted when they were under 18.

Speaking at yesterday's sentencing application, barrister Clive Grossman SC told the court the matter involved a 'unique sentencing operation' and urged that the cases be dealt with quickly because the prisoners had been behind bars for so many years.

Among the 12 former juvenile prisoners, Cheung Yau-hang was 16 when convicted with four other defendants of murdering Island School students Kenneth McBride, 17, and Nicola Myers, 18, in Braemar Hill in April 1985. It has been reported that his co-accused, Won Sam-lung, the youngest of the five, will be released on Tuesday. He was jailed when 16 and is now 35.

Mr Justice Pang fixed the cases to be heard between October 18 and December 22. Cheung's case will be heard on December 10.

A Department of Justice spokesman said 10 more cases would be listed for mention on Monday before Mr Justice Pang.