The house was built in 1997 without planning permission

Pembrokeshire National Park Authority was seeking an injunction to remove a turf-roofed house at Brithdir Mawr, near Newport.

The solar-powered earth and wood hut contravenes planning rules.

The couple who built it in 1998 were told to demolish it two years ago, but have refused to comply with the order.

The authority has always maintained that no new homes would be built within the national park unless there were overwhelming reasons to justify it.

The battle moved on to a new stage on Tuesday, when the authority asked the county court for an injunction. The hearing was adjourned when the judge - behind closed doors - urged both parties to consult and, hopefully, reach an agreement and avoid further litigation.

Tony Wrench and Jane Faith have lived in their roundhouse for eight years.

The park authority has repeatedly refused retrospective planning permission for the building.

Defiant: house builder Tony Wrench

Last year, its occupants were prosecuted twice for refusing to comply with an enforcement order to take it down.

A spokesperson for the authority said the court hearing was the latest stage in a "long process" concerning the roundhouse.

"The county court injunction is being sought by the authority as a means of finally resolving this long outstanding case," she said.

"We await the outcome with particular interest."

In a further development, however, the authority has recently discovered a second roundhouse built by Mr Wrench without permission.

Made of straw bales, it is 7ft tall and stands 50ft away from the original roundhouse and measures 18ft by 12ft.

He told BBC Wales he built it two years ago during a course for people wanting to know more about making roundhouses - and at a time when he and his partner feared they would lose their home.