The family was moved from a roadside lay-by to a lorry park in Brecon
A row has broken out over a decision by Powys council to locate a temporary gypsy camp in the Brecon Beacons National Park.
The park authority has accused the council of a "flagrant disregard of planning policy" and may consider legal action over the site near Brecon.
A permanent camp is planned nearby, but the council wants to locate 12 caravans at a small holding until that is ready.
It said it would apply to the park for retrospective planning permission.
The site under dispute is in an area known as Cefn Cantref.
At the moment the family of gypsies live in a lorry and coach park in Brecon, having recently moved from a lay-by in nearby Libanus.
Powys council said it had agreed in principle to create a permanent site for the family at Llanfilo, near Brecon, and a report about the project was expected to go before councillors in September.
In the meantime, the council said the lorry and coach park was not a suitable and it had decided to move the family to Cefn Cantref temporarily.
A spokesman for Powys council said: "The council has decided to locate the family on a vacant small holding at Cefn Cantref on a temporary basis until the permanent site is ready.
"It will be applying for retrospective planning permission for a temporary site to the Brecon Beacons National Park."
But the council's decision has angered the Brecon Beacons National Park authority.
Its chief executive, Chris Gledhill said the site at Cefn Cantref contravened planning policy.
He added: "We have been in liaison with Powys County Council for well over a year and clearly indicated that some of their proposed sites were more suitable than others.
"Cefn Cantref was not one of these sites and in fact, we made it very apparent that any development at this particular location is contrary to national park planning policy."
Mr Gledhill said he was concerned about the way the situation had been handled by the council, and he said the park would be forced to seek legal advice and guidance from the Welsh Assembly Government if the plans went ahead.
At a meeting to discuss the issue on Thursday, park officials expressed their "extreme disappointment" at Powys council's "flagrant disregard of planning policy by agreeing to an unauthorised development in open countryside in the national park".
It has asked for an urgent meeting with the council on Friday.
Michelle Davies, a community councillor for Cantref, said Powys council had not consulted residents about the plans for the temporary site.