Australian shares declined further on Friday, pushed down by miners and energy firms as commodity markets weakened. Australia's benchmark index fell 0.75% or 33 points and closed at 4,396.00. Woodside Petroleum dropped 2.2%, Origin Energy deteriorated 2.2% and Santos lost 3%. Caltex Australia slipped 1% after the Australian Competition and Consumer Commission said it has started an investigation into the sharing of price information among gasoline retailers.