Energy Resources of Australia Ltd (ERA), the producer of a tenth of the world's uranium, delivered a 31 per cent drop in output for the quarter after restricted access to the open pit.

ERA produced 1,030 tonnes of uranium oxide in the second quarter of calendar 2008, compared to 1,490 tonnes in the previous corresponding quarter.

The uranium miner said the drop in output was due to restricted access to the higher grade ore in the bottom of the pit at the Ranger mine in the Northern Territory, following heavy rainfall in the region.

ERA shares gained 40 cents, or 1.67 per cent, to $24.36 by 1046 AEST.

The uranium miner said it was able to access the higher grade ore in the last two weeks of June and lift the mill head grade from 0.22 per cent uranium oxide to 0.31 per cent.

Output during the six months to June 30 was six per cent lower than the previous corresponding period at 2,357 tonnes of uranium oxide.

ERA is 68.4 per cent owned by Rio Tinto Ltd and the Ranger operation is located about 250 kilometres east of Darwin in the NT.