They accused the Government last night of hiding the true scale of the problems as they produced figures nearly double those published by the Department for Health, which only records last-minute cancellations.

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The Tory figures – which reveal there were more than 12,000 cancellations in Yorkshire – were obtained through Freedom of Information requests to each health trust and show more than 7,000 patients had their operation cancelled more than once.

The Tories branded the figures "simply unacceptable" while patients said they were subjected to an "increasingly cavalier" standard of care as theatre booking issues, bed shortages and staffing issues were blamed for the majority of cancellations in the region.

But health trusts accused the Tories of being "mischievous" and said many of the cancellations were made by patients themselves or were administrative changes made before patients were even informed of their operation date.

About three quarters of NHS trusts – 124 – responded to the questions by the Tories, reporting 77,302 operations being cancelled for non-clinical reasons in 2007-08, which would amount to approximately 105,000 if the other trusts followed the same pattern. Some 11,585 of the operations were cancelled by patients.

The figures are much higher than official Department of Health records which show there were 57,350 cancellations in 2007-08 – up from 50,505 in 1997-98 – largely because the Government only records those called off by the NHS 24 hours or less before treatment, which Ministers say is the priority.

York Hospitals Trust reported 7,236 operations cancelled, the second highest, with 1,312 patients having treatment delayed more than once. At least one patient's operation was cancelled six times. It said more than two thirds of the cancellations were made by patients or represented changes before the patient was aware of the original date.

Leeds Teaching Hospitals Trust, one of the biggest in the country, had 1,396 operations cancelled, more than half because of a lack of beds.

Across the region missing patient notes, a lack of hospital transport or preparation issues were blamed for a small number of cancellations. Some were at the request of the GP or consultant and 718 were simply because more urgent cases came in.

The biggest offender for cancellations was Kingston Hospitals NHS Trust in south-west London, where 10,351 ops were called off. Trusts also reported in some cases a patient's operation was cancelled up to nine times.

Government targets have been blamed for hospitals fiddling figures on cancellations in the past.

After the Department of Health ordered a crackdown on late cancellations, one hospital, St George's Hospital in Tooting, South London, was accused of cancelling appointments in advance to avoid patients being sent home on the day.

And in 2005, the then Prime Minister Tony Blair said it was "unacceptable" for operations to be cancelled after a woman had her treatment delayed seven times.

Tory Shadow Health Secretary, Andrew Lansley, said: "Having an operation cancelled can cause huge distress for patients and their families. It's simply unacceptable that these figures are so high – and that the Government is spinning the official statistics to try to hide them."

The director of communications at the Patients' Association, Katherine Murphy, said: "Everyone understands that in an emergency, a patient may not have the operation they need because the clinical priorities of another must take priority.

"The examples in this survey, however, reveal a situation where patients and their families are subject to an increasingly cavalier standard of care in which the NHS is not putting patients first."

But the deputy chief executive for York Hospitals NHS Trust, Mike Proctor, said: "This interpretation of the statistics we supplied in good faith is a mischievous use of the information.

"Of the 7,267 reported cancellations, 5,360 were not genuine 'cancellations' in the sense implied by the Conservative Party. For example, 2,645 of these were planned operation dates cancelled by the patient themselves. In 2,715 cases the hospital changed the date in advance of the patient being notified of their operation."

A spokesman for Leeds Teaching Hospitals said it had cut cancelled operations by two thirds since April, adding: "Any league table based on actual numbers is bound to be an inadequate way of comparing performance.

"Leeds is one of the biggest hospital Trusts in the country treating around a million patients every year, so even by matching national standards the number of operations cancelled will be correspondingly higher than in other trusts."

A Department of Health spokesman said less than 1.5 per cent of patients had operations cancelled at the last minute.

He added: "Cancellations at any stage can be inconvenient for the patient but it is necessary to focus our attention and tackle the problem that causes most distress to patients first. Therefore, we collect the number of operations cancelled for non-clinical reasons at the 'last minute', but not the total number cancelled."