MILAN - A division of mining group BHP Billiton is holding a closed tender to sell a liquefied natural gas (LNG) cargo from Australia’s North West Shelf export plant, trading sources said. It was not clear whether the cargo had yet been awarded, they said. A recent change in the way the North West Shelf project markets LNG cargoes means that the six equal shareholders in the facility will from now on sell cargoes individually. The shareholders are BHP Billiton, BP, Chevron , Japan Australia LNG (a joint venture of Japanese firms Mitsubishi and Mitsui plus Shell ) and Woodside.