A BBC investigation has found that 60% of inspected hospitals in England who underwent spot-checks by the Care Quality Commission (CQC) were miscalculating their own performance.

According to a Panorama programme, the troubled Stafford Hospital was among the hospitals which provided the CQC with erroneous data.

In 2009, the CQC looked at 28 of the 144 acute hospital trusts in England. The inspections at Peterborough Hospital Trust showed that it had inaccurately reported its performance in three of four key areas.

The CQC checked four of the 44 'core standards' which were self-checked at 28 hospitals. It found that nine hospitals inaccurately reported one of the four standards, six failed two out of four standards and two trusts were wrong about three out of four standards.

'Medical intelligence' company Dr Foster release their own patient safety tables for hospitals in England.

Professor Brian Jarman, who works out mortality rates for Dr Foster, said: "My view is that patients do not realise that hospitals are self-assessing. I could hardly believe it until I read it."

Professor Jarman said that he was surprised that Stafford Hospital, which he had pinpointed for years because of its high death rates, was still classed by the health service as a 'fair' hospital.

"I really could hardly believe that they would say and publish that hospitals are good when we're saying that there are very, very bad and had been for 10 years," he added.