Public sector workers should be given higher praise, the government's spending watchdog has said.

James Strachan, chairman of the Audit Commission, told a Liberal Democrat fringe meeting that the government's preference for private partnerships had led to a devaluing of public services.

"There is far too little praise for people in the public sector. It's the collective view that the public sector is not quite up to it; it's not this marvellous private sector that can do a marvellous job," he said.

"We need to rebuild our trust in the NHS. We have it at a personal level but not at national level."

Public sector workers were a valuable resource, he said.

"Far too often there's such a search for a technology that's going to do the job magically when we all know it's actually about people not the tools they use," said Strachan.

The watchdog also challenged critics for their failure to offer credible alternatives.

"Too many people are philosophising and criticising and not enough people are coming up with solutions," he said.

He urged politicians of all parties to understand the local context of many problems facing the public sector and to allow local officials to be able to innovate.

"The man who makes no mistakes makes nothing," he argued.

Strachan warned of the dangers in setting rafts of targets at national level and counselled against one-size-fits all solutions.

"If these things are so simple, why don't you have shining public services all over the country," Strachan said.

"There is also a real danger that if you're not careful you set partial targets that can be met in the short term which distorts the system."

Equally he argued monopoly public services should be "tamed" rather than being left to their own devices where they would not meet the needs of people.

Strachan, who has a background as a City high-flyer, said the public sector should not focus on trying to recruit from commerce.

"People do not work in the public sector for money. They want to be paid properly but relativity is very important," he said.

"If people want to work in the City, let them stay in the City. They probably won't bring the same degree of passion you want for changing the world."