Contractors' bills top £600,000 – each

In the 2009-10 financial year, the Personal Accounts Delivery Authority (PADA) – a subsidiary of the Department for Work and Pensions – ran up a 9m bill on consultants.

But as of March 31, it employed just 14 individuals in such roles – suggesting an average cost per person of nearly 643,000.

The core Communities and Local Government department spent 37m on consultants in 2009-10, and was employing 75 people at the end of March. That suggests an average cost of more than 492,000 each.

It is the first time information has been collated on the total number of people working for the Government.

Departments have previously provided figures for their total spend on consultants, but declined to say how many they employ.

David Cameron has signalled that the annual 1.5bn consultancy bill will be one of the coalition's main targets as it seeks to cut public spending and tackle the deficit.

Cabinet Office Minister Francis Maude said the coalition had asked for the staffing details to be prepared so it could "get a grip on numbers".

"Today's figures may be a bit rough and ready, but we have to start gathering this kind of information straight away so that we know what the total workforce of government really is," Mr Maude said.

"Until now we've only had an incomplete picture of the true numbers of people working for us.

"But as we continue to push forward with our efficiency agenda, we need to ensure managers have this kind of basic management information.

A Downing Street spokesman denied that the preparation of the information was directly related to plans to cut jobs, but confirmed that staff numbers are expected to come down "over time".