Parents of private schoolchildren in the Illawarra are paying up to 9 per cent extra for school fees this year, despite increased levels of government funding.

In the past 12 months school fees for Illawarra private and independent schools rose by more than the Consumer Price Index inflation rate.

Cedars Christian College at Unanderra ramped up fees for Year 11 students by 9 per cent to $4928, despite a NSW government funding increase of 130 per cent since 2003, to $1.45 million.

Federal Government funding to the school has also grown by 43.4 per cent, to $2.34 million in the same period.

Edmund Rice College increased its annual fees for Year 11 students by 8.8 per cent to $2890, although its headmaster, David Lear, said the percentage increase looked worse on paper because its fees were lower than many other schools historically, given the facilities the school offered students.

When faced with the choice between cutting back services or increasing fees, the school was left with just one option.

"Our school fees are all inclusive and quite low, so any increase is going to work out to be a bigger percentage than a school with higher fees," he said.

Mr Lear said the college had given 14 per cent of families fee concessions in 2008 and an increase in students wanting to access the special needs unit run by the college - at an annual cost of $300,000 - was putting additional pressure on the school's budget.

"We receive $125,000 from the Federal Government for our special needs program, the rest comes from us," he said.

NSW Greens' education spokesman John Kaye, who calculated the funding increases using federal budget estimates and state expenditure, said the figures were another stark reminder of the failure of state and federal government private school funding policies.

"Fees continue to rise despite massive increases in private school funding," Dr Kaye said.

"The federal and state governments claim that giving $2.3 billion a year to NSW private schools makes them more affordable. It's a myth.

"Meanwhile, public schools are left without adequate funding."

Acting executive director of the Association of Independent Schools NSW, Michael Carr, said independent schools had to meet the rises in education costs or change the nature of their education provision.

"In recent years the increases have been in the region of 5 per cent to 8 per cent per year. The main costs for independent schools are teacher salaries and capital costs," Mr Carr said.

"Independent schools get very little government funding for capital development, such as building and refurbishment of classrooms, libraries, school halls and other facilities, so these must be paid for out of parents' pockets through fees, donations and fundraising."

Combining both state and federal funding, public support for a student in a government school is on average $10,715 each year, but for a student in an independent school it can be as low as $1570. On average total government funding for an independent school student is $5050.

The recent round of fee hikes follows a trend of large increases since the introduction of the Howard government's controversial socio-economic status (SES) funding scheme.

Fees at St Mary Star of the Sea College have jumped almost 100 per cent in the past six years.

However, headmistress Fay Gurr said the increases, though substantial, were a cautionary measure, for forecast loss of government funding under the SES system and to finance the school's multimillion-dollar building program.

"There was a big leap after 2000, which was a prudent decision by our board, to prepare for changes in funding under the Federal Government SES scheme and also, at the time, our building program became very real," she said.

"We feel we've made good provisions for the future and I feel we are now in a position where we can reign any further increases to 4 or 5 per cent a year."

Ms Gurr said the school had made the provisions so as not to burden parents with a sudden fee hike.

"Our belief here is that education should be open to all people and we want to make sure we put ourselves in a price range where that is possible," she said.

Member for Throsby Jennie George said the Federal Government had promised to keep the previous government's SES system of funding and was concerned parents were still being made to pay more out of their own pocket.

"The non-government school sector has had an amount for funding maintenance ... over and above the current SES funding arrangement," she said.

"I would have thought the additional funding should have worked to lessen any impost on families choosing to send their children to non-government schools.

"It concerns me that fees have been raised above inflation even under more generous funding arrangements," she said.