Carole Evans, president of the Girls' Schools Association, said: "We must question whether this Government's oratory over partnership will ever be matched by action."
Ministers announced a new era of co-operation with private schools in 1997, with the independentstate schools grants scheme. They said the independent sector was "an integral and valuable part of the national education system".
Until now, independent schools have publicly supported partnership. But this week, Mrs Evans told the GSA's conference in Manchester of "apparent discrimination against teachers in the independent sector".
She said teachers at private schools could not access New Opportunities Fund money for ICT training, funding for the National Professional Qualification for Headship or initial teacher training if they were in an independent school.
Help with loan repayments for teachers in shortage subjects was not available for those joining private schools, she added. And she criticised suggestions that private school teachers should pay to join government sports training schemes while their schools provided training venues for free.
"If this is partnership, I am not quite sure what the benefits are for us," she said, to cries of support from the audience. "If we are to be partners then surely it is time that we were treated as equal partners."
Mrs Evans, who is headmistress of Birkenhead high school, said that private schools had always had partnerships with state schools. "Individual schools have always worked together - we do not need government money to encourage us to do that."
But she criticised the Government's attitude to the partnerships, saying they were "not two-way".
Earlier, she warned that over-assessment was threatening the education of less affluent pupils in private schools. These pupils no longer had time for Saturday jobs to help pay their fees. Mrs Evans said around 40 per cent of her pupils had such jobs.
A senior civil servant addressing the conference hinted that the Government was considering whether to reduce the amount of external testing for 14 to 19-year-olds.
Rob Hull, director of qualifications and young people at the DfES, said:
"People are saying that, cumulatively, the amount of assessment imposed on students is now quite a substantial burden which has implications for the exam system. We want to reflect on that, and also on the nature of assessment."
He was also considering whether the assessment for vocational qualifications was too academic.