Aluminium producer Comalco Ltd has postponed a decision on whether to build a $1.4 billion alumina refinery in Australia by another week as it finalises back-up plans in case gas is unavailable from Papua New Guinea.

Chief executive Mr Terry Palmer said yesterday an announcement on whether to proceed with the plant in Gladstone, Queensland, or Bintulu, Malaysia, would be made within the next 14 days. A decision had been expected by the end of this month.