Councils in Sussex spent more than £15 million on temporary and agency staff in just a year.

The GMB union is accusing councils across East and West Sussex of wasting tax-payers' money after it compiled a list showing how much each one spends on temporary staff.

Brighton and Hove City Council came high on the list of Sussex authorities, spending £4.5 million during the financial year from 2005 to 2006.

Only East Sussex District Council spent more - £5,072,000 out of its total salary costs of £115,760,000 - according to its own report on staffing costs.

Crawley Borough Council spent £1,142,800, followed by Hastings with £744,240 and Worthing with £595,000.

Smaller councils such as the district authorities covering Horsham, Rother, Lewes and Mid Sussex were further down the list.

Richard Ascough, the GMB's regional organiser, said council's were wasting money as they had to pay agency fees on top of the workers' salaries.

He said: "This is a horrific abuse of the public purse and is tantamount to back door privatisation.

"GMB members working in the public services are rightly appalled at the waste of public money as a result of management's failure to put in place adequate levels of permanent staff."

Michael Coughlin, chief executive of Crawley Borough Council, said the council often employed casual staff to work at events such as pop concerts at The Hawth theatre and to make up the numbers on refuse collections, where there were rules about the minimum number of people allowed on each lorry.

He said: "We sometimes bring in temporary or agency staff because of the seasonal nature of the work they are doing, such as grass cutting or maintaining flower beds. It's more cost-effective to bring in somebody from an agency."

He said it often took several months to replace highly trained staff, such as planning officers or in-house solicitors, when they left or were on maternity leave and the council sometimes took on temporary staff to cover their posts.

A Brighton and Hove City Council spokesman said: "The sum represents just 3.7 per cent of our wage bill. Equivalent permanent staff would also cost taxpayers millions and this is ignored in the GMB figures.

"However we are actively reducing agency costs by developing our own staff pools. We already have the Care Crew for social care staff and will next month launch Admin All Areas to maintain a supply of good admin staff."

West Sussex County Council couldn't provide a figure for the amount it spends on temporary staff but a spokesman said: "It is unrealistic to expect a large organisation such as the county council, which provides 80 per cent of local government services, not to employ temporary staff.

"We often need temporary care staff to ensure that vulnerable people continue receiving services when permanent staff are on sick leave. We would also employ temporary staff for maternity cover."

Arun District Council said 95 per cent of the £554,810 it had spent on temporary staff had gone to consultants who brought in expertise the in-house team could not provide.

A spokeswoman from Adur District Council said: "We always employ temporary or agency staff as a last resort and where we can't fill a post. Sometimes this can be for specialised posts or short term projects. The only area we have a specific budget for temporary staff is refuse, recycling and street cleaning. For this we have abudget of £75,000."

The £209,468 spent on temporary staff was a tiny part of the council's £8.8 million staffing budget.