The relationship between mining company ERA and traditional owners of the Ranger uranium mine site has showed signs of serious deterioration.

Senior traditional owner Yvonne Margarula says the company was lying about the timetable for the planned expansion at Ranger.

She fears any new works will mean that mining will continue beyond the scheduled completion date.

ERA is scheduled to finish mining at the Ranger site by 2021 and after rehabilitation to leave the site by 2026.

But after its annual general meeting on Wednesday, company chief executive Rob Atkinson left open the possibility that the timetable might extend.

"We don't have any plans to go past 2021, however if further discoveries are made and they do appear to be attractive we would work closely with our stakeholders," he said.

ERA is currently seeking government approvals for two new projects at the Ranger mine - one to extract uranium oxide from low-grade stockpiled material, the other to explore an underground mine.

"All our current plans at this point in time are built around finishing the operation in 2021," Mr Atkinson said.

"I cannot categorically say an extension won't be applied for."

That sort of talk has angered Ms Margarula.

"They said they were going to finish by 2026 and they were lying to us," she said.

Ms Margarula has called on ERA to commit to that date.

Her attack represents a serious breakdown in the relationship between ERA and the Mirrar people.

"I clearly understand the sensitivity that the traditional owners have about their land and that they are keen for the operation to finish in 2021," Mr Atkinson said.

"We've been very up front about all our plans that we've got in place at the moment."

If those plans blow out the company, will have to reach a new agreement with the Federal Government and the Northern Land Council on behalf of Ms Margarula.