County Hall spent almost £18million on interim staff in the last financial year, and has already spent £13.3m this year.

The figures, released under a Freedom of Information request, also revealed that four of the interim staff were being paid £800 per day during contracts lasting up to almost four years.

The highest paid post, an education estates strategy manager, received £825 per day with a contract lasting two-and-a-half years.

In contrast someone aged over-21 paid the minimum wage working an average 7.5 hour day would earn just £48.75.

Not all interim staff would be working five days a week, but would provide consultancy work at various points during the contract.

In total Essex County Council (ECC) spent £17,952,632.51 on interim appointments in 2013/14, with more than 200 paid above £300 per day last financial year.

A spokesman said many of the payments were set at an industry rate and needed to attract top talent to the roles, while other interim staff were used for things such as maternity leave cover.

Some of the posts were also filled by interim staff as a permanent employee for the post could not be found.

David Finch, council leader, said: “Interim staff at ECC costs around 1% of our total spend this financial year and they play a vital role in the way we offer better value for money to the taxpayer.

“We have achieved £450m savings over the last five years and are on course to deliver a further £237m over the next three years. Providing value for money to residents is at the very heart of what we do at County Hall and in order to make these savings it is important that on occasions we bring in staff to deal with high-level skilled work.

“The use of interim staff is considered on a case-by-case basis and evaluated through rigorous controls which are in place around the recruitment of temporary staff including benchmarking pay to ensure best value for money.”

Julie Young, leader of the Labour group at ECC, said this was an issue her party was doing some research on and would look at in their budget amendment.

She said: “Some will be justified, if for example going through a period of change and we want staff with certain skills. But some of these seem to be much more established posts where we would be better employing them on a permanent contract.

“It does not seem right that we are paying that kind of daily rate to consultants when we are having to lose our own well-established staff in redundancies.

“We have asked Essex to become a living wage authority, which would affect about 135 staff and cost just £150,000 – a drop in the ocean when you are paying some staff £800 per day.

“Essex also has the highest number of senior staff paid more than £100,000 in England, and there are certainly questions to be asked as to how we structure our workforce.

“Given we are going to lose £49m from government I don’t think this is sustainable.”