The Public and Commercial Services Union said the review threatens to bring cuts in jobs and public services.

But a Scottish Government spokesman insisted the review “is not a cuts agenda”.

He said: “Our aim is to work as effectively as possible with the resources we have been allocated.”

The 7,500 staff employed by the Scottish Government were told of the review, entitled: Shaping Up - an effectiveness and affordability review of the Scottish Government.

The union said the review is a vehicle for “unprecedented” cuts to jobs and services for the first time since devolution.

It comes a week after it emerged senior civil servants were making plans for the SNP administration to introduce a 5% cut in public sector spending, as well as tax increases, to keep Scotland’s finances under control.

Labour said a 5% cut in spending from every single Scottish Government department, with no exceptions, would amount to cuts of about £2bn a year. It said this was “far greater” than the £500 million the SNP alleges has been deducted from next year’s Scottish budget.

PCS Scottish secretary Eddie Reilly said of the review: “There is only one conclusion - this is not about shaping up but is about shipping out.

“It is the beginning of public servants and public services in Scotland paying the price for the banking crisis and the recession.”

Mr Reilly said his union had held an emergency meeting to discuss it and added: “The sole purpose of trade union engagement in this process will be to defend our members’ jobs and the services they deliver.

“We will fight for the priorities of the people, not the greed of bankers.”

But Scotland’s most senior civil servant, permanent secretary Sir John Elvidge, said the goal since 1999 had been for the civil service in Scotland to be recognised as the most effective of its kind in the UK.

“In 2007, important and radical changes were made to the way in which we organise the civil service in Scotland, this is a good time to build significantly upon those changes,” he said.

“As civil servants, we have to make sure that where we have resources, we are focusing them on the right activities and that we’re not spending any more than we need in the process.

“Our aim is to make sure we are delivering the best possible public value for Scotland, whatever budget we are allocated over the coming years.”