Uranium miner Energy Resources of Australia said Wednesday it would have to buy uranium to cover contractual commitments after disappointing production from its Ranger mine in Australia.

Lower ore grades at the mine have resulted in lower than expected production, leading ERA to revise its 2010 production estimates downward to 3,900 mt of uranium, from earlier estimates of between 4,300 and 4,700 mt.

"Additional supply requirements necessary to meet 2010 sales commitments, anticipated to be around 5,000 mt, will be mostly covered by purchases," the company said.

Profits will be hit, ERA warned, since "the small price margin associated with the sale of the purchased material is more than offset by the on-going costs of operation."

ERA is 68% owned by Rio Tinto. Uranium oxide production by ERA for the 2010 third-quarter was 911 mt, 10% higher than the previous quarter and 35% lower than the corresponding period in 2009.