Seventy-five schools are expected to be eligible. They will receive $290,000 in cash grants a year per additional class, allowing them to split students in classes of 20 to 25 for Chinese, English and maths, compared with normal class sizes from 32 to 37.

Nelson Lau Chi-keung, chairman of the Subsidised Primary Schools Council, said the government was over-simplifying education issues as a problem of equity.

'Socio-economic status of students is only one of the factors affecting their educational outcome,' Mr Lau said. 'Poor students are not doomed to academic failure, just as rich students are not problem-free.

'There are lots of factors, including special learning needs, teaching pedagogies, school culture, all of which are irrelevant to family backgrounds of students.'

He also said the government was overlooking the majority of families who could neither qualify for the new measures nor afford private schooling for their children.

'The aim of small classes is to increase attention for students and enhance teaching effectiveness, and all students should be entitled to quality education, ' he said.

The association supported an approach, which had been approved in a Legislative Council motion, of implementing smaller classes in districts seeing a sharp decline in student population.

Raymond Jao Ming, chairman of the Eastern District Parent-Teacher Association, said the proposed measures might have a labelling effect on poor students.

'The measures are discriminatory in nature, and give an impression that poor students are more prone to academic and behavioural problems,' Mr Jao said.

'We also feel that the government is causing class segregation in education, which has been united in fighting for smaller classes in the past, by giving priority to disadvantaged students.'

Legislator Cheung Man-kwong, also president of Professional Teachers' Union, said he was happy to see that the government was moving towards smaller classes.

But he criticised its proposed plans as a 'bad way to implement a well-intended policy'.

'The government has to brace itself for not only criticism from the education sector, but also from the many parents who will go to all lengths to fight for equal education opportunities for their children,' Mr Cheung said.

The government launched a three-year pilot scheme implementing small classes in 37 primary schools in September, starting with Primary One, to determine the effectiveness of smaller classes.

Professor Hau Kit-tai, chairman of the Department of Educational Psychology at Chinese University of Hong Kong and a member of the research team monitoring the schools, said it was too early to identify conclusive findings.

But he supported the EMB's strategy for extending the initiative. 'It is following international practice to start as early as possible, and to start with disadvantaged groups,' he said. Reducing classes for students from poorer families had the greatest impact, he added.

Arthur Li Kwok-cheung, Secretary for Education and Manpower, said the government did not intend to further extend small classes in the near future.

'The Education and Manpower Bureau is in principle supportive of the broad direction of small class teaching and believes that a strategic implementation approach should be adopted to optimise the benefits of small-class teaching,' Professor Li said during a Legislative Council meeting on Wednesday.

The EMB will meet with schools to discuss small-class teaching in an education panel meeting next Monday.