A row has broken out over future plans for leisure services in Swansea.
Unison has accused Swansea council of reneging on a promise not to privatise services as part of saving money.
The union claimed three private contractors have been shortlisted to run Morriston, Penlan and Penyrheol sports centres.
But the authority said no decisions have been made and that if partnerships were formed with outside organisations, it would not be privatisation.
The union said privatisation would be "a terrible error" which will damage the quality of service for the public and employees' working conditions.
Chris Cooze, from Unison, said: "Swansea council has panicked and gone for a short-time economic fix with a privatisation that does not benefit the local community. Outsourcing is never the answer.
"Private companies are interested in pound notes not quality of service to the public and experience shows when leisure centres are outsourced, charges to users increase and opening hours are reduced.
"When this happens there is no-one to complain to because there is no democratic accountability if leisure centres are not council-run. Local people want a say in how their services operate."
The council called the union's comments "untrue and very disappointing" because they will cause unnecessary worry for staff.
A spokesman added: "There are a number of options for running leisure facilities, as we already see in Swansea at a number of facilities and in other local authority areas across the UK.
"All of these options are being explored, including retaining 'in house', setting up a new charitable body, or considering a partnership with organisations that operate within a not-for-profit trust model, have a community interest or charitable aims. This would not be privatisation.
"If a decision is made at the end of this process to work in partnership with an existing third party to run our facilities, then we're confident no jobs will be lost and that levels of access and affordability will be maintained."