Former NSW education minister Adrian Piccoli – one of the strongest champions of the original Gonski agreements – has broken ranks with his own government to support the Turnbull government's new school funding model.

Mr Piccoli told Fairfax Media it would be the "biggest own goal in education history" if Labor, the Greens and the Senate crossbench unite to vote down the government's bill this week.

Former NSW education minister Adrian Piccoli has thrown his support behind the Turnbull government's school funding model. Credit:Kate Geraghty

Mr Piccoli's stance contrasts with that of his successor as education minister, Rob Stokes, who has said anything less than delivery of the full six-year Gonski deals was unacceptable to NSW.

Mr Piccoli's intervention came after Fairfax Media revealed secret modelling shows public schools would lose up to $4 billion over a decade if the new model is voted down while Catholic schools would be $4.6 billion better off.