Three-month copper on the London Metal Exchange (LME) added 2% to $ 8,556.50 a tonne after climbing to $ 8,633. Prices are up about 9% this month.
The advance of copper on the LME replicated movements in China, where the most traded copper contract on the Shanghai Futures Exchange rose almost 6% to 63,290 yuan ($ 9,784), the highest since September 2011.
The basis for the rebound is demand from China, expectations of tight supply and a flood of speculative investments. Many analysts predict a multi-year bull run.
But the market may be moving too fast, Commerzbank analysts said.
“There is no new data available to support the steep rise in metal prices, particularly in recent weeks,” they said. “Metal prices are being driven largely by speculation and the rally is beginning to look excessive.”
Copper stocks in deposits registered with the LME total 76,025 tonnes, close to its lowest level since 2005. The three-month spot copper premium over metal is increasing, suggesting a shortage of supply nearby.