Primary care leaders have joined the argument over extended hours after GPs warned they may refuse to take part in local audits on opening times.
The British Medical Association's GPs committee has advised practices they are within their legal rights to withhold data being requested by primary care trusts on practice opening hours and the availability of appointments.
But Primary Care Trust Network director David Stout accused the BMA of "making a big fuss" and called the move "unhelpful".
"I wouldn't want to go down the legal route, but as I understand it, PCTs can ask for information that's reasonable," he said.
GPs committee deputy chairman Richard Vautrey told HSJ: "Our legal advisers have told us that GPs do not have to provide this information. PCTs need to be reasonable in their approach. There's lots of information that practices already provide about surgery opening times and the range of appointments. There's no reason why they need to be seeing specifics about individual appointments."
The information "varies tremendously" from week to week, meaning "it would be unreasonable to pin the whole practice down to a point in time," he added.
PCTs were asked to carry out the audit by Department of Health director general of commissioning and system management Mark Britnell in a letter last month.
The dispute follows the BMA's climbdown last week, when it decided to accept changes to the general medical services contract which will force GP practices to open longer. Dr Vautrey said the motion had been passed "overwhelmingly" but it was not a unanimous decision.
The government had said that unless practices agreed to stay open for three extra hours a week, they would strip 135 points from the quality and outcomes framework.
The BMA will poll its members in the next few weeks to decide whether to accept the offer formally. Mr Stout said there were signs that GPs would support it.
Although the quarrel had largely taken place between the government and the committee, a no vote would make it more difficult for PCTs to stand back, Mr Stout said. "A lot will depend on long-standing relationships between PCTs and GPs."
An NHS Alliance spokesman said: "GP practices and PCTs should be working together on a basis of mutual trust and respect and the sooner we can get back to that the better."