SYDNEY, March 25 (Reuters) - Australia on Wednesday unveiled A$2 billion ($1.40 billion) in support over 10 years for Rio Tinto's RIO.AX Boyne Smelters, the country's second-largest aluminium smelter, to stay open.

The investment, equally funded by the federal and Queensland state governments, will unlock almost A$7.5 billion in new investment in Queensland, with Rio Tinto underwriting investment in energy assets, Federal Industry Minister Tim Ayres said.

Australia's metals processing sector has been under pressure from high energy and labour costs, and governments have announced financial support for several facilities last year.

($1 = 1.4296 Australian dollars)

(Reporting by Renju Jose in Sydney; Editing by Mark Porter)

((renju.jose@thomsonreuters.com;))