Education chief Michael Suen Ming-yeung appeared to suggest the government was preparing to review the mechanism for determining whether schools were allowed to teach in English or Chinese.

Speaking to a Chinese-language newspaper earlier this week, Mr Suen said drawing a line between English-medium secondary schools and those teaching in Chinese created 'serious labelling problems'.

While he said this could not be solved by simply 'taking down one label and sticking up another', he called on schools to give suggestions on the way forward for the mechanism ahead of the revised system's implementation in 2010.

However, the Education Bureau has since stressed that there are no plans for a policy shift.

'It is not the government's objective to overturn the existing medium-of-instruction policy,' a bureau spokesman said in a statement.

'We are only aiming at making adjustments to the implementation details on a needs basis, to ensure that the policy could better align with the present circumstances and needs of the community.

'There must be a proper mechanism for implementing the policy and for facilitating stable school development.'

Nevertheless, Sister Wong said she was concerned this could mean the bureau was planning to adjust the policy to enable English-medium schools to avoid switching to using Chinese, even if they failed to meet the requirements.

'We saw that there were some English-medium schools that were not doing very well,' she said. 'If you allow these to continue using English to teach it would not be fair on other schools.'

Sister Wong was on Education Commission working group that produced the 'Review of Secondary School Places Allocation and Medium of Instruction for Secondary Schools' report in December 2005.

The report - which was adopted as policy by the then Education and Manpower Bureau - recommended that, from 2010, schools would need to ensure at least 85 per cent of their Form One admissions were capable of learning in English in order to use it as the medium of instruction.

Schools planning to switch the medium of instruction in 2010 are to make the decision by the end of the 2008-09 school year, after which they would be subject to review once every six years.

Local students in the top 40 per cent of academic ability are deemed capable of learning in English.

Sister Wong said the working group had also been concerned about the labelling effect on schools, but had been unable to reconcile that with the 'unusual situation' in Hong Kong, due to the conflict of opinions on which language students should learn in.

'We spent two years looking into every possible solution to this problem, but there is none,' she said.

Shirley Wong She-lai, chairwoman of the Subsidised Secondary Schools Council, said her association was also at a loss to why the issue had resurfaced.

'We don't know why they brought this up again all of a sudden,' she said. 'We have not been calling for a review as we thought the policy had already been laid down.'

Ms Wong said the council's original position had been that all schools should follow a bilingual model, but had accepted the working group's proposals.

'We have not formulated a position for the time being,' she said. 'We support mother-tongue education and are not going to ask for the whole policy to be overturned.'

However, she said there was some concern that the school system might face similar turmoil as in 1998, when the introduction of the mother-tongue policy ordered all but 112 secondary schools to switch to teaching in Cantonese.

Wong Kwan-yu, chairman of the Hong Kong Federation of Education Workers, also expressed surprise.

'It seemed like it had all been settled before,' he said. 'We are against starting from the beginning again.'