Investors anticipate strong demand for copper in the new year
The price of copper has reached a 16-month high with strike action looming at two copper mines in Chile.
Copper on the London Metal Exchange traded above $7,300 a tonne on Wednesday - its highest level since September 2008.
Investors expect demand for the metal to be strong in the new year.
There are also concerns that strike action at the two mines owned by Chile's Codelco - the world's largest copper producer - could affect supply.
Expectations of higher demand will add to the long rally in copper prices seen in 2009, analysts said.
Copper is now on course for an annual rise of about 140% - its biggest in more than 30 years.
Strike action at the giant Chuquicamata and Mina Sur mines in Chile is due to begin on 4 January, though analysts are not expecting prolonged disruption.
Workers are calling for pay increases, prompted by the rise in global copper prices.
The Chuquicamata mine alone produces around 4% of the world's copper, according to RBC Capital Markets, and is expected to produce 565,000 tonnes of copper this year.