Energy Resources of Australia (ERA) has upgraded its full-year uranium production guidance as its expects to pump the last water from its flooded Ranger mine by mid this year.

The uranium miner was in 2011 affected by an exceptionally heavy wet season in the Northern Territory that prevented mining at its Ranger 3 Pit although the company still managed to shift its stockpile of uranium ore to market.

Shares in ERA were up 1.5 cents, or 1.19 per cent, at $1.275 against a negative broader market.

ERA, which is majority owned by Rio Tinto, on Tuesday said it expected its Ranger mine would produce between 3,200 and 3,700 tonnes this calendar year, up from a previous forecast of 3,000 to 3,700 tonnes.

The upwardly revised guidance came as the miner reported production of 612 tonnes for the March quarter, up 18 per cent compared to the same period last year when extreme rainfall flooded the mine, prompting a lengthy suspension of output.

ERA said it had raised its annual forecast because it expected to re-commence mining at the Ranger Pit 3 later this month, which was earlier than anticipated, although de-watering was expected to continue until July.

"Production for 2012 remains highly dependent on the level of actual rainfall encountered for the remainder of the year," the company said in a statement.

ERA's March 2012 quarter production was down 41 per cent compared to the December 2011 quarter, reflecting lower grade ores sourced from stockpiles.

While high-grade ore at the bottom of the pit will be accessed when de-watering is complete, uranium grades at Ranger are generally falling as the existing open pit is becoming depleted.

ERA plans to shift its focus from the open pit to the underground Ranger 3 Deeps resource, which it hopes to develop into a mine.

The company said it would significantly step up exploration activity in the Ranger project area until 2014.

ERA shares have fallen substantially in recent years as a result of internal and external woes, reaching $18.40 at the height of the mining boom in 2007.