UPDATE 1-Origin Energy's Beharra gas plant shut due to fire

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SYDNEY, Dec 27 (Reuters) - Origin Energy Ltd (ORG.AX), Australia's second-largest power retailer, said on Thursday a fire at a gas plant in Western Australia had caused a temporary shut down of the plant.

The Beharra Springs gas plant, a joint venture between Origin and Arc Energy Ltd ARQ.AX, produces about 10 terajoules of gas per day. The Beharra plant output accounts for about 3.5 percent of Origin's total daily gas production, an Origin spokeswoman said.

The fire has been extinguished and the plant is expected to be back in operation before the end of January, Origin said in a statement.

There were no injuries to any workers during the incident, while the cause of the fire was not yet known, Origin said in a statement.

The Beharra plant is 67 percent owned by Origin, while Arc has a 33 percent stake.

Origin shares were up 1.1 percent at A$8.70, while Arc shares slipped 0.4 percent at A$1.29 in a firm overall market .AXJO. ($1=A$1.15) (Reporting by Denny Thomas; Editing by James Thornhill)