Copper rose by 2.92 percent on Friday on weak US economic data and a firmer euro, to close strongly on the London Metal Exchange (LME), traders said.
"It's been a curious session today. The market had seemed settled for the weekend, but that all changed after the US data," a trader said.
The dollar fell sharply after news the US trade deficit widened much more than expected to a record $55.5 billion in June. The greenback slumped further after the University of Michigan's index of consumer sentiment fell to 94.0 in early August, from 96.7 at the end of July
Copper firmed to $2,853 a tonne by the close on Friday, from $2,772 on Thursday.
"From a weekly close perspective this is the strongest close since April," the trader said.
Traders said a series of buy stops had been triggered which drove prices higher
"We have a very good move higher today. The main driver has been CTA buying in a very tight market and a major shift in the euro-dollar exchange rate," Barclays Capital analyst Ingrid Sternby told Reuters.
The market was now aiming at technical resistance $2,860/65.
Traders said they expected strong physical premiums and three month prices in the fourth quarter of the year as exchange stocks and inventory held by China's Strategic Reserve Bureau, dwindled.
Traders said the SRB likely held between just 50,000-80,000 tonnes of metal, down from a peak estimated around 300,000 tonnes.
Aluminium firmed to $1,728 from $1,715.
"Aluminium has been steady. It has met denser trade selling above $1,725 but in the short term $1,750 is a reasonable target," the trader said.
Stocks fell below 800,000 tonnes on Friday for the first time since December 2001.
"The technical trend has improved and there is significant upside potential," Sternby said.
Nickel was up $150 at $13,350, while tin was also firmly entrenched in ranges closing $40 higher at $8,840/50 higher.
Lead fell to $870 from $887, while zinc broke though $1,000 to close at $1,002, versus $987 at Thursday's kerb.