UP to 500 new jobs are to be created by the expansion of NT's only uranium mine.

Most of the construction workers will fly in and out of Darwin and stay at a camp near Jabiru. They will work on digging an underground mine and a heap leach plant at Ranger. Both projects will take about two years.

Energy Resources of Australia boss Rob Atkinson told the Northern Territory News about the jobs after announcing Ranger made a record $127.6 million profit in the past financial year - $38.9 million more than in the previous year.

Mr Atkinson said the profits boost was due to increased sales and better prices for uranium oxide.

The underground mine has been given approval by the Federal Government and an environmental assessment is being carried out for the heap leaching operation.

Both projects are opposed by environmental groups.

The number of miners is unlikely to increase dramatically. The main pit will be exhausted by 2012 and the workers would move to the underground and heap leaching operations.

ERA has discovered huge new uranium deposits in the past year - as much as has been mined since Ranger began 20 years ago.

The mine's federal lease expires in 2012 and Mr Atkinson was reluctant to speculate on what would happen if, as expected, even more uranium is found over the next few years.

Industry observers believe Ranger has the potential to run for at least two more decades.