The force was one of four highlighted for particular criticism by Paul Ginger, chairman of the federation's inspectors' central committee, for its lack of progress in combating stress levels among inspectors and chief inspectors.

Mr Ginger said: "The failure to act is disappointing and detrimental to the morale of the rank of inspector.

"Chief inspectors and inspectors have a strong commitment to their profession, the demands of the role and the extensive hours they have to work.

"However, over a period of time, such strong levels of commitment are unlikely to be sustainable if excessive workloads and lack of work-life balance prevail."

The survey, carried out in 2008, found many inspectors had been bullied, with colleagues and managers getting the blame.

But Assistant Chief Constable Derek Talbot defended the force's handling of any reports of bullying, and added low sickness rates were testament to the overall wellbeing of officers in the county.

He said: "We responded to the original survey. We looked carefully at the federation recommendations and could see no significant improvements to the way in which we currently support the inspecting ranks in their challenging role.

"Northamptonshire Police has one of the lowest sickness rates in the country and one of the lowest sickness rates due to officer injury in the country. As a result, we have been able to put more officers out on the streets, policing local communities, which is what the public have told us they want to see."

* ADVERTS were published nationally yesterday for the role of Chief Constable of Northamptonshire Police, whose current incumbent, Peter Maddison, leaves on June 21. The advert calls for a "strategic leader of exceptional calibre" who has the desire to take the police into the "top performing quartile" of forces. The advertised salary is £126,471 plus benefits.