Hundreds of council workers will stage a 24-hour strike tomorrow in a dispute over plans to transfer staff to the private sector.
Unison members at Barnet Council in London will take industrial action, warning of a "mass outsourcing programme", which the union said could lead to large numbers of employees moving to the private sector over the next year.
Branch secretary John Burgess said: "The council is gambling that the private sector can deliver £100 million savings over the next 10 years. We have seen no evidence to substantiate these claims.
"In other parts of the country we have seen the consequences of such blind allegiance to 'public sector bad, private sector good'.
"Our members are not daft, they can see that redundancy and cuts to jobs and services are behind the transfer from the council to a private sector contractor.
"Strike action is always a last resort, but for the last three years we have been asking for a genuine dialogue with the council to explore ways to save money, improve services."
The council's deputy leader, Daniel Thomas, said the strike was "disappointing", adding: "We will do all we can to make sure services to residents will run as normal. We have made a very generous offer in terms of protecting membership of the local government pension scheme.
"Staff would remain in the local government pension scheme and this strike is about the name on the bottom of a pay slip and which employer contributes to that pension. I'm sure that's a level of certainty a lot of Barnet residents would envy."