The number of staff employed by Oxfordshire County Council has jumped by almost a third over the past decade.

In March 1997, County Hall - the biggest employer in Oxfordshire - had 15,947 on its payroll. But by March last year, the latest figures available, that number had grown to 20,819 - an increase of 4,872.

The figures, obtained using the Freedom of Information Act, take into account all staff, including part-time and job share employees.

County Hall said the rise was largely explained by an increase in teaching posts, more duties and responsibilities being given by the Government and services being taken back by the council, like Cogges Museum in Witney.

However, the authority was unable to supply the Oxford Mail with details of its wage bill for the 10 years since 1997.

Former Oxford Lord Mayor John Power, who made the FoI application, said: "At a time when they are charging me £40 to park my car (for an on-street parking permit), here we have a mass increase in staff numbers and a dramatic reduction in service. They may be an excellent council, but they are an excellently expensive council with too many staff, doing too little, being paid too much. And all this is when the Tories promised us an efficiency drive. The jump is unbelievable - what are they doing, where do they put them all?"

In March last year, Oxford City Council employed 1,400 staff at a cost of £43.4m, the Vale of White Horse District Council had 319 staff costing £9.8m and South Oxfordshire District Council had 275 staff at £8.9m. West Oxfordshire was unable to supply any information.

Earlier this year, the Oxford Mail revealed that County Hall's most senior employees had been awarded 10 per cent pay rises.

Chief executive Joanna Simons earns £173,766 - a pay rise of almost £15,000. The directors for environment, social and community services, children and community safety now each earn £122,106.

In October 2005, the authority was forced to axe a controversial job as it was deemed a waste of money. County Hall advertised for a corporate social inclusion officer - a £55,000 post even leader Keith Mitchell admitted baffled him.

John Howell, the council's cabinet member for change management, said: "Since the present cabinet came into power in 2005, non-school staff numbers have been monitored closely and stringently as part of a rigorous control of our employee levels.

"The effect of this has been to hold staffing levels at a stable level.

"Every single request for a new post is rigorously tested against need and budget."

Mark Fysh, branch secretary of public sector union Unison, said: "Unison is concerned the expansion is flawed in that we have more and more layers of chiefs and the money has not gone on the expansion of Indians."