UPDATE 2-Apache to partially resume Australia gas output

(Adds statement from Western Australian government in paragraph 5)

PERTH, Aug 1 (Reuters) - U.S. energy firm Apache Energy Ltd (APA.N) plans to resume gas output at its gas plant off Western Australia slightly ahead of schedule, after an explosion in June knocked out a third of gas supplies to a key mining region.

Gas from the Varanus Island plant off northwest Australia will be available at an initial rate of 110 million cubic feet per day (mmcfd) in the next few days, Apache said in a statement on Friday.

That would be about 35 percent of the plant's total output.

"In coming weeks, the production rate would increase to 220 mcf per day with full production of 300 mcf by the end of the year," Apache Managing Director Tim Wall said in a statement.

Apache did not give a firm restart date. But the Western Australia government in a separate statement said Apache's gas suppy was expected to commence by Aug. 6.

Apache had earlier said it expected to restore natural gas production of 180 mcf by Aug. 15 and planned to resume full production by December.

The explosion on June 3 led to power crunch in Western Australia state, causing production shutdowns and reduced operations across a number of industries, including mining, agriculture, construction, hospitality and manufacturing.

The shortage also triggered a dash for alternate energy supplies from industrial customers such as global mining giants BHP Billiton Ltd/Plc (BHP.AX)(BLT.L) and Rio Tinto Ltd/Plc (RIO.AX)(RIO.L), while Alcoa Inc (AA.N) declared force majeure at its Australian alumina operations.