Union leaders have hit out at a move by Cambridgeshire County Council to activate a clause in employees’ contracts that will force them to take three days of unpaid leave.

The authority says the dire financial situation has meant it needs to find an additional £14.6million in savings this year, and says activating the clause has become necessary for the first time since it was inserted into contracts in 2014.

But leaders of Unison have branded the move “cruel” and called on the council to reverse the decision.

Unison Cambridgeshire county branch secretary, Rob Turner said: “This lay-off is an unwanted Christmas present for Cambridgeshire’s hard-working council staff.

“When the emergency agreement was reached four years ago, we had no idea austerity would last so long. To blow off the cobwebs and pull it off the shelf now is a cruel blow to the dedicated staff who work so hard to keep the county running.

“Council bosses want to present this as three days off at Christmas, but in fact it’s a 1.2 per cent pay cut for staff who’ve already suffered years of pay freezes.”

The council has said it will need to find an additional £14.6m in savings during 2018/19, on top of savings already planned when councillors set this year’s budget in February.

According to the council, £8million of these savings have already been found but time is running out to find the additional savings.

By law, the county council has to set and maintain a balanced budget.

The county council had previously negotiated with trade unions a clause in all employees’ contracts to impose a period of up to three days unpaid leave if the financial situation made it necessary – and this year, for the first time, the council says it is necessary.

As a result, except for statutory services, the county council will close on December 27, 28 and 31, and all but the lowest paid staff (those earning less than £26,470 per year) will take these days as unpaid leave.

This will contribute £900,000 to closing the budget gap, and is the saving the council could otherwise achieve by cutting around 40 full time posts.

Work continues to set next year’s council budget and to bridge the estimated £20m gap for 2019/20 with proposals being finalised to be discussed at committees during October and November.

A spokesman for the county council said: “The mandatory unpaid leave provision has been part of a collective agreement that the council signed with unions in 2014, but given the council’s current financial position this is the first year we have had to activate it.

“We’re implementing it specifically to protect jobs and services. It will save £900k, and the alternative would be losing something in the region of 40 posts.

“The period chosen to apply the leave is at time where there is least demand on most services – so when work is unlikely to ‘back up’.

“Staff will have the money deducted from their pay in 12 equal amounts from November – and a number of lower paid staff who can take leave out of their annual holiday entitlement have already asked if they can ‘opt in’ and purchase the additional days through this advantageous process.

“Our essential services will continue to operate, and we’ll be publicising a list of these by the end of October.

“We continue to take our concerns about funding to central government. Through our FairDeal4Cambs campaign, we are working with local MPs to lobby government on an improved funding formula, for Cambridgeshire which is the fastest growing county in the UK, yet the 3rd worst funded per head of population.”

Union eastern regional secretary, Chris Jenkinson said: “In Birmingham, Theresa May proudly declared that austerity was over. She clearly hadn’t talked to Conservative councillors in Cambridgeshire.

“This enforced lay-off is the thin end of the wedge for jobs and services. This year it might just be the 2,000 staff earning more than £25,000 who have to take unpaid leave over the Christmas break – next year it could be everyone.

“Council bosses need to stand up and fight to get ministers to fund local government properly, not pick the pockets of loyal staff in a desperate attempt to keep local services running.”