Speculation has been increasing that the Henry tax review has recommended a 40 per cent resource rent tax, charged on operating margins and based on the petroleum resource rent tax.

The tax, which would replace state-based royalties of 2-10 per cent of revenue, would be vehemently opposed by the states and companies.

Rob Atkinson, chief executive of the uranium miner, said he was watching the situation closely because mining companies were important in giving the Australian economy strength.

"If there are going to be impacts on us, I hope that is going to be thoroughly explained and our perspective sought," he said.

"It is a concern and we have quite a number of constraints that we have to face on a day-to-day basis without having further ones added. It really is watch this space for the industry at the moment."

Mr Atkinson made the comments as ERA reported a 23 per cent rise in annual profit. The Rio Tinto subsidiary booked a net profit for the year to December 31 of $272.6 million, up from $221.8m in 2008.

The company hit records in savings and revenue, driven by the higher price it received for uranium, and strong production results.

Mr Atkinson said the company's strategy was to focus on long-term contracts, set four to five years ahead, which were 99 per cent of its business.

On the back of last year's strong results, the company expects costs to increase this year because of a cycle of maintenance on its mine and development on its Ranger 3 Deeps project in the Northern Territory. "It is about spending money to ensure we are setting ourselves up for the future."