Stubbornly high prices for contracted gas on the east coast have driven Brickworks to invest $126 million in a new, more efficient production plant at its western Sydney site as it seeks to eke out supplies of the fuel that are costing more than double spot prices in the domestic and international market.

"You've got to pull costs out somewhere," said Brickworks managing director Lindsay Partridge, noting that the company's gas supply contract with Santos is priced at "north of $10 [a gigajoule]", well above short-term rates.