SYDNEY - Origin Energy Ltd, an Australia energy retailer, said on Monday its share of the cost of buying Woodside Petroleum Ltd's Otway gas project will fall to A$507.2 million ($463.2 million).

Origin said in a statement the fall is due to one of the other partners in the project choosing to exercise a pre-emptive right to increase its interest. ($1=1.095 Australian Dollar) (Reporting by Denny Thomas;)