Middle-class families will be the hardest hit by the English Schools Foundation's new HK$500,000 debenture scheme, a parent group said.
The move would "for sure and 100 per cent" affect middle-class parents, Hong Kong Parents Association secretary Henry Chan Sing-tat said.
"They may have been able to afford it before, but now they won't - or they'll be really stretched," he said.
Under the scheme announced yesterday, parents who pay the HK$500,000 will gain priority placement for children if they meet ESF admission requirements and pass interviews.
Chan said the association opposed paying to ensure a school place or to move up in priority, but the decision was a business call, and his group could not comment on business decisions.
"In our opinion, education and school placement should not involve money - apart from school fees," Chan said.
"Money should never be a factor in whether a child gets a spot or not. It should be based on ability and other assessments."
The chairman of the Federation of Parent-Teacher Associations of Hong Kong Eastern District Raymond Jao Ming said the debenture would make ESF schools unaffordable for some parents.
"Only the upper classes will have enough money and this will definitely only further divide the rich and the poor," he said.
Jao said ESF schools' interactive and lively teaching methods were attractive to local parents, but now many of them might not be able to afford them.
A government spokeswoman said the government was reviewing its funding policies with the foundation concerning "ESF schools' important position in Hong Kong's education system".
The government would also take into consideration needs of expatriates' children in Hong Kong, and continue to hold discussions with the ESF.
"We noticed that [the debenture] is to fund school improvement projects at ESF schools, which will ultimately benefit students," an Education Bureau spokeswoman said.
The government "will not micro-manage ESF's day-to-day operations", but it would call on the ESF to give out clear details of the debenture policy to parents.