Parents of thousands of pupils at schools run by the English Schools Foundation, the largest English-language education provider in the city, will pay 4 per cent more on average from this year, after the bureau approved the increase.

Now, a total of 63 international and DSS schools have applied to the bureau for fee adjustments, compared to 53 DSS schools that did not do so.

The Hong Kong International School was one of those that felt a need to boost its income.

Its chief advancement officer, Erik Dierks, said the management had gone to great lengths in slowing the pace of fee growth, but had run up against rising costs.

"We have always wanted to keep [the rate increase] as low as possible. The reason we [still] do it is market driven," Dierks (pictured) said yesterday.

"We need to retain the best faculty in the world, and the costs include housing for staff, which goes up with inflation."

The school was seeking to add up to 4 per cent to its current charges, he said. The latest bureau figures show 36 international schools and 27 direct subsidy schools, including elite institutions with a strong focus in foreign-language training, had applied for fee increases for the 2012/13 academic year.

Most of those DSS schools asked for single-digit rises, said Chan Wai-kai, external secretary of the Direct Subsidy Scheme Schools Council.

Chan noted that under a new school management scheme, schools were barred from making high-risk investments and should cut fees if they accumulated a large surplus.

The scheme was set up after some schools were found to have invested heavily in property and stocks.

One of the DSS schools that notified the bureau it would not raise fees in 2012/13 was St Paul's Co-educational College Primary School.

"Our financial situation has remained sound since the last fee increase three years ago," said Kim Tsoi, the school's director of community relations. He said a fee rise would be avoided when unnecessary.

Most schools popular among expatriates raised fees by as much as 10 per cent over the past two years, the found in a survey of international schools.

The ESF followed its fee rises announced in April with a new debenture scheme on Wednesday that asked parents to pay a non-refundable HK$500,000 to reserve a place for their children in 2013 and beyond.

The expatriate community has been complaining about the years of school fee increases that have made English-language education in Hong Kong less affordable.

Observers say a lack of such school places, coupled with an influx of local and mainland children whose parents are seeking alternatives from the standard Hong Kong curriculum, have prompted schools to raise charges.