Leicestershire CC and Leicester City Council are arguing about who should pay the redundancy costs for staff who cannot find work in either council by April, when Leicester becomes a unitary.
Leicestershire has issued precautionary redundancy notices to 600 of its staff. Many will be appointed to jobs before April, but the rest will be made voluntarily redundant or retire early.
'The two authorities need to get together and sort their dispute out and stop using staff as political footballs,' said Unison national officer Owen Davies.
Whichever council takes responsibility for them will have to pay their redundancy costs.
The county and the two councils taking on some of its services next year, Rutland DC and Leicester, agreed in October to take a share of the 1,650 county staff who would not transfer automatically into a job after reorganisation.
Leicestershire argues the city should take on 600 staff along with about a third of the county's budget. The county will take responsibility for 1,000 people and expects to find jobs for most of them.
The city has not specified what number of staff it wants to take on. It too has staff who may not find work by April, and says the county should take these people into account when calculating how to divide redundancy costs. This was not a proviso of the national agreement.
In an attempt to force the city's hand, Leicestershire chief executive John Sinnott has issued the redundancy notices, mainly to middle managers and administrative and clerical staff.
'It's an action the county very much regrets having to take,' said Mr Sinnott. 'It was something that had to be done to protect the council's financial position.'
Leicester leader Peter Soulsby said last week that issuing redundancy notices was totally unnecessary and invited the county to return to the negotiating table.
Leicester's senior employee relations adviser, Mike Powell, said the city would not be issuing any redundancy notices at this stage.