Warning as cheap PNG labour tempts Exxon EXXON Mobil may more than double the size of its $US16 billion ($16.57bn) Papua New Guinea liquefied natural gas plant amid waning enthusiasm for onshore plant development in Australia, where it has called for labour relations reform. Yesterday Exxon's Houston-based head of Middle East and Australian development, Mark Nolan, talked up the attractiveness of PNG as an investment destination while Australia's high labour costs and low productivity were affecting investment decisions here.