Copper prices advanced to their highest level in nearly nine years on Tuesday, boosted by optimism about a global economic recovery that bodes well for metal demand while supply is expected to remain tight.

Benchmark copper on the London Metal Exchange rose as much as 0.5% to $8,437 a tonne in early Asian trading hours, rising for a third straight session to its highest since May 2012.

The metal, often used as a gauge for global economic health, was up as much as 9.4% from its Feb. 2 low of $7,712 a tonne.

A weak US dollar also helped boost the appeal of greenback-priced copper.