Copper prices extended gains on Tuesday to touch their strongest in three weeks on signs of firmer demand and shortages in China, as well as supply worries after more attacks in the Middle East. Benchmark three-month copper on the London Metal Exchange climbed 0.4% to $13,590 a metric ton in official open-outcry trading after touching $13,638, its highest since June 23. “Copper is finding support from a combination of strong Chinese export data and tightening physical market conditions,” said Ewa Manthey, commodities strategist at ING. Data showed that exports in top metals consumer China surged in June in their best ... (full story)