Ministers clashed yesterday with health experts over whether public satisfaction with the NHS is holding up despite the harsh economic climate.

The King's Fund health policy think tank reports today the biggest ever drop in satisfaction, from 70 per cent in 2010 to 58 per cent in 2011, based on data from the British Social Attitudes Survey which has been used as a barometer of public opinion for almost 30 years.

But ministers countered with a Mori poll showing satisfaction remaining high at 70 per cent. Both polls had similar-sized samples of around 1,000 and were conducted at similar times last year, when controversy about the NHS reforms and budgetary pressures was at its height.

A ministerial source suggested a possible reason for the difference was that the King's Fund data came from a wider survey of social attitudes, and responses on the NHS may have been negatively influenced by other questions about the poorly performing economy. The Health Department's Mori poll, which has been run annually for 12 years, is a discrete survey, not subject to the same influences. But neither side was conceding ground yesterday in the war of the satisfaction statistics.

John Appleby, chief economist at the King's Fund, said satisfaction as measured by the BSAS had risen every year for almost a decade from 2001, the start of the biggest funding boom in the NHS's history, and the rise had to come to an end eventually. It was the scale of the fall that was unexpected.

NHS waiting lists had remained stable and hospital infections had continued to come down between 2010 and 2011 – two key measurers of performance about which patients got most worried – so they could not explain the decline in satisfaction. The fall was evident across all political parties, and among recent patients as well as those who had not made recent use of the NHS.

Ministers were in part to blame for increasing gloom about the NHS because of their habit of highlighting its failings. There were also concerns about the disruption caused by the Government's reforms, now being implemented following the passage of the Health and Social Care Bill, and the need to find £20bn of savings by 2015.

Professor Appleby said: "It may be that a combination of ministerial rhetoric to justify the reforms, concern about the reforms themselves and reaction to the funding squeeze combined to create worries about the NHS and dent the public perception it is being run well."

Simon Burns, the Health minister, countered that the right people to ask about the NHS were those who had recently used it. "The British Social Attitudes Survey targets the general public rather than people that have actually used the NHS, so responses are influenced by other factors," he said.

The latest survey of 70,000 NHS patients showed 92 per cent rated their treatment as good, very good or excellent.

"We want all patients to get excellent care from the NHS. The Care Quality Commission is carrying out the biggest ever programme of unannounced inspections. We are also introducing a friends-and-family test which will give detailed feedback on whether staff and patients think their hospital is providing good care," he said.