Almost 10 per cent of hospital managers have admitted altering figures to meet government targets, in a poll published on Monday.

Since coming to power in 1997, the government has set targets on a range of services, including waiting times in accident and emergency wards, cancer treatments and the number of outpatient appointments, with funds allocated to meeting them.

However, a third of those questioned for the BBC could recall examples where such money was spent on other services, including primary care, mental health and administration.

"Good people's principles are being compromised because it's only a brave person who can stand up for them and not lose the ability to pay their mortgage or maintain their families," one manager said.

Another claimed to have made a 100 per cent return to the Department of Health on waits in their A and E department, because they considered the target to be "meaningless."

The survey also found that more than half of managers will not raise concerns with senior staff, for fear of the consequences.

Members of the Institute of Healthcare Management were interviewed for the study.

Stuart Maples, chief executive of the Institute, warned that staff should feel free to complain.

"The NHS will only flourish in an atmosphere of openness where whistle blowing is always encouraged and people feel comfortable raising issues," he said.

"Successful organisations have open cultures and they are better places to work in for it."

Chief executive of the NHS, Nigel Crisp, said that "significant improvements" were in the pipeline.

"Delivering healthcare is tough. We are trying to make sure we provide significant improvements over the next few years, and this means we have to be focused and disciplined," he said.

"Where managers have shown they can deliver results we are prepared to lift the hand of Whitehall and give them more freedom to improve services locally.

"But we have seen in the past a tiny minority have failed to live up to the standards of the majority - in manipulating waiting list figures, for example."

The NHS is to launch a new code of conduct for NHS managers on Wednesday.