Australian S&P/ASX 200 traded flat on Tuesday, erasing early gains as worries about Greece and Portugal debt problems returned to markets. Australian benchmark index declined 0.02% or 0.9 points and settled at 4,224.20, supported by the jump in oil prices. Energy shares climbed, while mining stocks showed mixed performance. White energy soared 3.8%, Woodside Petroleum Ltd advanced 0.7% and Coalspur Mines added 3.1%. In contrast, nickel producer Mirabella Nickel fell 13.17%. Trading volumes were low, as Chinese markets and still closed for New Years holidays.