Councils taking steps to introduce a four-day week for their staff have been told by Rishi Sunak's government that they should “stop immediately”.
Secretary Michael Gove's department has warned local authority bosses that the practice should not be adopted.
Ministers at Leveling Up, Housing and Communities (DLUHC) argue that the experimental new work arrangement is not delivering value for money for local taxpayers.
It follows a row earlier this year over the trial of a local authority run by the Lib Dems, which offered staff a three-day weekend in exchange for longer shifts.
In September, South Cambridgeshire District Council announced it would extend the pilot scheme until next March – despite ministers previously ordering officials to end it.
Unveiling new guidance, Tory local government minister Lee Rowley said: “Councils that continue to ignore this guidance now know that the Government will take the necessary steps over the coming months to ensure that this practice ends within local Authorities. “
If councils defy guidance and there are signs of a decline in services, the government says it can “raise concerns directly with the authority, monitor performance more closely and consider options to correct declining performance”.
Mr Rowley added: “Under normal circumstances the Government naturally respects the right of councils to make their own decisions on key issues.”
“There are also times, however, when the Government considers it proportionate to step in to ensure that residents' value for money is protected. The issue of the four-day work week is one of those times.”
However, South Cambridgeshire District Council – the first local authority in the UK to carry out such a trial – is continuing its trial despite the guidance.
The local authority says there is strong evidence that a three-day weekend helps with recruitment and retention.
Since January, sickness rates have fallen by a third and complaints about services involved in the pilot scheme have fallen, the authority said.
Council leader Bridget Smith said: “On the one hand, the government is telling us to innovate to cut costs and deliver higher quality services. on the other hand they tell us not to innovate in order to provide services”.
“We are best placed to make these decisions in our region, which has high wages and housing costs in the private sector, making it very difficult to attract and retain the talented staff we have to offer residents and businesses.”