RIO shares added 4.9pct to $65.63 while BHP Billiton ( BHP ) gained 3.2pct to $36.85. The mining sector was the best performer, following sharp gains on the London Metals Exchange on Friday night on hopes of a resolution to the European debt crisis. Economic data released today showed the broad measure of business inflation, or final stage prices, rose by 0.6pct in the September quarter, in line with forecasts.