This is the finding of a new report that coincides with the re-emergence of school funding wars, with Federal Education minister Simon Birmingham conceding that some private schools are over-funded.

Centre for Policy Development researchers Chris Bonnor and Bernie Shepherd found that students at mid-range Catholic schools in Victoria received 105 per cent of the state and federal government funding that similar state school students received.

The average government funding per student at a mid-range Victorian Catholic school was $9832 in 2014, compared to $9384 for a similar public school student.

Students at mid-range Victorian independent schools received an average of $8587 in government funds.

Most Australian schools fit within this range, and have an Index of Community Socio-Educational Advantage (ICSEA) of between 950 and 1150.

Mr Bonnor, a retired principal and public education advocate, said funding inequities were "endemic" in Victoria compared  with other states. He said this was because state government funding for Victorian public schools only increased slightly between 2009 and 2014.

In New South Wales and Queensland, the researchers found that government funding of mid-range state schools always exceeded the government funds that flowed to non-government schools.

"It defies logic and the very framework of public and private schools in Australia. One sector is meant to be privately funded and the other publicly funded," Mr Bonnor said.

"We now have a private sector that is substantially government funded, and they have different obligations and accountabilities. Public schools have to be available for every child, in every community, under every circumstance and private schools don't have those same obligations."

He said private schools were also able to charge parents as much as they liked in fees.

But Catholic Education Melbourne executive director Stephen Elder said the researchers' findings were based on a "fundamental misunderstanding about school funding".

He said that the Catholic system allocated funding to schools based on its own formula. "These formulas differ and reflect different perspectives on what schools are estimated to need based on their individual circumstances," he said.

It comes as the federal government commences negotiations with the states and territories over a new four year school funding model to replace Labor's Gonski agreements. The Andrews government is calling on the Turnbull government to commit to the final two years of the current Gonksi agreement, and says Victoria will miss out on almost $1 billion of funding if it fails to honour the agreement. Victorian Education Minister James Merlino has also failed to commit to funding the final two years of the needs-based agreement.

A Victorian government spokesman said the Andrews government was repairing the previous state government's neglect by investing more than $5 billion in the education system.

"It is our way of giving every student in every postcode the best opportunity for a great start in life, and making Victoria the Education State," he said.

On Monday, Mr Birmingham was asked on ABC discussion program Q&A whether wealthy private schools were over-funded.

"There are some that fit that bill, yes, there are," he said.

Victorian state school students receive the least state and federal government funding in the country, with the most recent data showing they each received $2253 less in state and federal funds than the national average in 2013-14.