Copper and crude oil edged higher yesterday as risk appetite improved after Greece dropped plans to hold a referendum on a European Union bailout. Investors remained jittery, however, and volumes were generally light as Greek Prime Minister George Papandreou faced a cliff-hanger vote of confidence later in the day after having backtracked on his shock-call for a referendum. \"The market is purely sentiment-driven at the moment; risk sentiment keeps swinging back and forward but volumes are pretty low,\" said analyst Andrey Kryuchenkov of VTB Capital. \"People are hoping... Greece will do whatever the EU proposes and that the debt crisis won\'t spread.\" Three-month copper on the London Metal Exchange climbed 0.4 per cent to $7,942.50 (Dh29,173.21) a tonne at 12.50pm. The metal earlier hit a session high of $8,059.75 per tonne.