PCTs measure whether practices are able to offer GP appointments within 48 hours by asking when their first and third available appointments are.
GPs say that many PCTs inform practices when to expect the test call to avoid receiving a poor star rating.
Some PCTs even supplied locums to ensure appointments were available when the checks took place (GP, 9 August 2004).
Health minister Lord Warner last week announced that PCTs would no longer warn practices when test calls would be made.
Lord Warner told The Guardian: 'Mystery callers will telephone surgeries up and down the country on a random day every month to stop doctors fixing the results of their monthly returns.'
But GPC deputy chairman Dr Laurence Buckman said the remarks were 'unfortunate and clearly at variance with the truth'.
He accused Lord Warner of 'bandying around accusations masquerading as government policy', and said GPs were not to blame for any fixed results.
'Many PCTs phoned practices to tell them when to expect a test phone call, and told them specifically to make sure they had appointments available within the target limits,' Dr Buckman said.
'Most practices were conscientious and were meeting the targets anyway.'
In July 2005 PCTs told the DoH that more than 99 per cent of patients could see a GP within 48 hours or a primary care professional within 24 hours.
But a DoH statement last week said this was 'not fully consistent with reported patient experience'. It pointed out that a Healthcare Commission report in September 2005 found that just 88 per cent of patients could see a GP within 48 hours.
'Our thorough examination of GP access should help solve the mystery of why there is a real difference between what patients and practices report,' said Lord Warner.
'All patients should have fast access to a GP every working day of the month. At the same time, practices need to offer advance appointments. There must be no excuses or exceptions.'
GPC chairman Dr Hamish Meldrum questioned the merit of any 48-hour target.
'Improvements to seek to ensure that the 48-hour access target is measured accurately are welcome, but the changes will have little impact on how practical the target actually is,' he said.
Dr Meldrum said GPs would always see patients with urgent medical conditions immediately, but the target did not allow them to prioritise patients on the basis of need.