A High Court judge ruled in June that cabinet members had not considered the effect of the closure on disadvantaged people before pushing the decision through.
While public sector equalities duties were not met, the legal challenge against closing the facility was not upheld, meaning it could still close in the future.
The council is expected to pay half towards the claimant’s court fees, but the total cost to the authority remains unclear – despite an attempt to obtain the figure through a Freedom of Information (FOI) request.
But council leader Dave Poole has warned that “high impact” public services cuts would be needed to offset legal fees and the ongoing cost of keeping the site open, which stands at around £10,000 per month.
In an internal email seen by the Local Democracy Reporting Service, Cllr Poole urged Labour councillors not to debate issues surrounding Pontllanfraith Leisure Centre over email.
“This is a complicated case and the devil will be in the detail,” said Cllr Poole.
“I have asked officers to draw up a list of service cuts to cover the costs of the judicial review and the cost of keeping the centre open beyond its proposed closing date.”
Cllr Poole says the unexpected costs had not been included within the £15.5 million in cuts already agreed this year, with the local authority expected to find another £60 million over the next five years.
He wrote: “You will no doubt be aware that such cuts will be to services with high impact on the public, the low and medium impacts having been exhausted.”
A council spokesman said that any proposed cuts would be subject to wider consultation later in the year as part of the council’s budget-setting process.
Advice from the Chartered Institute of Public Finance and Accountancy also warns against local authorities using reserves to plug funding gaps, the spokesman added.
But Cllr Colin Mann, leader of the Plaid Cymru group, said: “Any costs as a result of the judicial review can be put down to the intransigence of the Labour cabinet.
“They want the public to pay for their gross incompetence in yet more service cuts.”
Cllr Mann added that public money had already been “wasted” on the ongoing senior officers’ pay dispute, with the current cost standing at more than £4 million.
The leader of the council’s Independents group, Cllr Kevin Etheridge, had asked the cabinet to put the decision to close Pontllanfraith Leisure Centre to full council – a request which was refused.
After submitting an FOI request for the total cost of legal fees, Cllr Etheridge was told that the figure had not yet been finalised as it was an ongoing matter.
“I think asking the ratepayers of the county borough to cover costs that could have been avoided is totally unsatisfactory,” he added.