Spot checks on abortion clinics ordered by health secretary Andrew Lansley are at the centre of a growing political row.
A leaked letter from the Care Quality Commission (CQC) has revealed it had to scrap 580 other inspections to complete Mr Lansley's unexpected order, costing it £1 million.
The health secretary's intervention was triggered by evidence that doctors at up to 20% of clinics were breaking regulations by signing consent forms for abortions without establishing the woman's circumstances.
His move led to the loss of the equivalent of 1,100 days spent on planning and inspecting, the CQC's chair Dame Jo Williams wrote.
"Such a request at short notice entails Operations management time in planning the visits, cancelling pre-planned inspections as well as the compliance inspector time in carrying out the visits and drafting the reports," she complained.
The Department of Health responded by saying that she had not raised such concerns when Mr Lansley gave her instructions for the extra inspections.
"We would expect the CQC, like any good regulator, to be able to prioritise its inspections and are told that in this case they did so, so that no patients were placed at risk," a spokesperson said.
"The CQC has around 900 inspectors, only some of whom were involved in these inspections the vast majority of which were completed in four days."
Its complaints have, however, reopened an abortion debate which has been developing momentum in recent months.
Conservative right-wing backbenchers like Nadine Dorries have been calling for action to make terminations harder than they are at present.
She told the Mail newspaper: "As the organisation which originally uncovered some very worrying practice within the abortion industry, they are now complaining about having to uphold and enforce the law which is exactly what they are there to do.
"They need to remember that this is about the health of women – it's not either/or, no health provider should be allowed to break the law."
Shadow health secretary said it was Mr Lansley who had questions to answer, however.
He said the health secretary had not offered a "proportionate response" in ordering the checks, called on him to publish civil service advice and questioned why he had briefed a newspaper about the emerging findings.
"These revelations today raise yet more questions about Mr Lansley's judgement, the way he is running his Department and his relationship with the independent regulator," Mr Burnham said.
"He owes people full answers if they are to be able to have any confidence in him as health secretary."