Base metals closed mostly firmer on Thursday on the London Metal Exchange (LME), driven by fund and technical buying, analysts and traders said.
"Early on we saw some short covering, then the funds got involved, we kicked over some stops and off we went," one LME trader said.
Traders said the market had been bound tightly in ranges for the previous five trading days, but a concerted marketing effort helped push copper through resistance around $2,800/05 a tonne.
"We did 4,300 lots of copper, more than the volume in LME warehouses. That's good volume," a second trader said.
Copper rose 1.95 percent or $54 to close at $2,823 a tonne by Thursday's last open outcry.
"If copper closes above $2,800 two days running we could be looking at a new range from $2,800 to $3,000. If the market fails to take it out then we'll be back between $2,700/720 to around $2,800," Man Financial analyst Edward Meir said.
The second trader said: "Analysts are talking higher numbers, but personally I can't see the big funds going in with heavy longs."
Traders said delays unloading at Chinese ports were putting pressure on the price of copper on the Shanghai Futures Exchange, which had a knock-on effect on the LME and COMEX.
"There's a lot of material in China, but it's sitting in containers waiting for customs. So there's a shortage of material getting to consumers," a US trader said.
Aluminium gained $5 to $1,713.
"Aluminium is holding up well. News of alumina shipment problems and the continuing stock falls are supportive," Meir said.
On Thursday Jamaican officials said two ports used to export alumina had been damaged by Hurricane Ivan and could be out of commission for up to two months.
Alcoa Inc said it would try to make alternative arrangements for exports from the Rocky Point port.
However, government mining officials said there was no obvious alternative option for shipments from Alpart's Port Kaiser facility.
LME warehouse stocks fell 1,125 tonnes to 701,700 overnight.
Nickel closed $150 lower at $13,000, while tin rose $135 to $8,985. Lead was $7 up at $888, but zinc fell to $988 from $990.