Ms Harman believes the report will reinforce Labour's commitment to replace fundholding, which she will underline in a speech today to the British Medical Association.
The NAO report is expected to conclude there is no evidence that fundholding has led to improvements in patient care or innovations in treatment, contradicting claims by ministers.
It will also criticise the system, under which GPs are given their own budgets to "buy" treatment from NHS trust hospitals on behalf of their patients, for raising administration costs in hospitals, health authorities, and among GPs themselves.
Ms Harman will use her speech to the BMA to dismiss reports that Labour has weakened its commitment to replace GP fundholding. She will tell the doctors' organisation that Labour will act immediately on taking office to abolish the internal market, under which primary care services compete to buy treatment from trusts, and to replace GP fundholding.
Under a Labour government, family doctors, health authorities and hospitals will be expected to form partnerships and to sign comprehensive health care agreements (CHAs).
"We want to see the earliest possible end to the market madness in the NHS," Ms Harman will tell doctors.
Senior Conservative backbench MPs privately reported yesterday that health is one of the three most important reasons constituents are giving for deserting the Conservatives, along with "betrayal" over increases in tax, such as VAT on fuel, and insecurity at work.Reuse content