An immigration detention centre or a defence facility may be part of a contingency plan to save the outback town of Nhulunbuy as crunch time for its future approaches.

A representative of mining giant Rio Tinto suggested scenarios for the town's survival at a meeting on Monday night, including a new detention centre or a defence installation, people who attended the gathering said.

The miner did not reveal any concrete plans.

Residents in Nhulunbuy, a town of about 4000 people in eastern Arnhem Land, are waiting anxiously to learn whether Rio Tinto will continue the local operations of its subsidiary Pacific Aluminium.

The huge alumina refinery and mine at Gove employ about 1400 people, nearly all of whom live in Nhulunbuy.

A downturn in alumina prices and the high cost of powering the remote plant, which runs on diesel that is shipped in, have pushed it into a loss-making position.

The NT government has been trying to arrange for a $900 million gas pipeline 600km long to be built to serve the operation.

The pipeline has been criticised as a bid by Australia's second largest resources company to blackmail the government into acting to give it cheaper power.

A spokesman for Pacific Aluminium said that interpretation was wrong, that the company would pay for the pipeline's construction but the federal government would underwrite the project.

"We would pay for the pipeline through a transportation tariff. We are not seeking any handout," he said.

Rio Tinto has set a deadline of January 31 for a decision on the future of the site.

It could decide to mothball the Gove operation until prices pick up, or close it permanently if the cheap power from the gas line isn't made available.

Ross Theedom, town administrator for Nhulunbuy Corporation Ltd that runs the town, confirmed a detention centre or defence installation were discussed at the meeting.

He said he was hopeful the gas line would be built though.

"Not a lot has been talked about in terms of the contingency, but they were looking at all sorts of projects," Dr Theedom said.

A small detention centre for illegal immigrants is currently located at the town.