Mr Suen said school groups had been petitioning for a wide range of measures, including having different language streams within a school, either on a subject-by-subject basis or by splitting students into English or Chinese classes according to ability.

But he insisted that schools would not be given carte blanche; rather, the bureau would implement an 'objective, transparent' mechanism to determine how schools could set their language of instruction policy.

He gave no details of what form that mechanism might take.

Mr Suen said the bureau aimed for 60 per cent of secondary school leavers to be capable of learning in English by the time the new six-year secondary curriculum was fully implemented in 2012. Now, only the top 40 per cent of Primary Six graduates is deemed able to learn in English.

There have been persistent rumours of a significant policy shift since November, when Mr Suen announced a review to 'fine-tune' a new set of rules on medium of instruction due to come into effect in 2010. Those rules, set down in 2005 after an extensive consultation process, had been in favour of maintaining the rigid divide between English- and Chinese-medium secondary schools and categorically ruled out language streaming within schools.

Mr Suen's comments yesterday were broadly welcomed by the education sector - on the condition that the change would not result in a return to the situation prior to the introduction of the mother-tongue education policy in 1998.

At that time, schools had complete autonomy over their medium of instruction, with many opting to teach in English regardless of whether teachers were competent in the language or students were able to learn effectively. The mother-tongue policy banned all but 112 secondary schools from teaching in English.

Professional Teachers' Union president Cheung Man-kwong said it was important to ensure students were capable of learning in English and the labelling effect of Chinese-medium schools was minimised. 'The most important thing Mr Suen said was there will be a clear mechanism for inspecting and making sure schools maintain standards.'

Dominic Chu Fu-yau, former chairman of the Subsidised Secondary Schools Council, said allowing schools to choose which classes to teach in English or Chinese was better than 'simply splitting schools between winners and losers'.

'Frontline teachers are the optimum judge of whether their students would learn best in English or Chinese,' Mr Chu said.

Michael Tien Puk-sun, chairman of the 2005 policy working group, said he did not believe the government was going to change the core findings of his team's report - that schools should only be allowed to teach in English if they could meet set criteria, including students' language ability, teacher quality and support measures within the schools.

'Initially, we had been in favour of allowing language streaming within schools, as we felt that was a more idealistic solution,' Mr Tien said. 'But in the end we decided there were too many practical concerns.'

These included the drain on resources due to the need to inspect quality 'class by class' and the increase in teacher workload from having classes in two languages. 'The key is, there needs to be a system of quantifiable ways to uphold conditions to allow students to learn effectively.'