LONDON, March 24 (Reuters) - Copper prices ended lower on Thursday, falling from almost three-week highs after new orders for U.S. manufactured goods fell unexpectedly last month, hinting at slowing activity in the world's largest economy.
Three-month copper on the London Metal Exchange CMCU3 closed at $9,712 a tonne from $9,727 at Wednesday's close. Earlier it rose to $9,784, its highest since early March.
U.S. copper futures' benchmark contract, May HGK1, settled down 0.4 cent at $4.4245 a lb.
"In the last few days, the macro data has been a little disappointing, not to mention the problems in Portugal," said analyst Dan Smith of Standard Chartered, referring to the resignation of Portugal's prime minister over rejection of austerity measures to solve a debt crisis.
"On the base metals I tend to be fairly neutral at this point ... there's talk in markets like steel about soft orders from Japan, premiums remain a bit depressed in copper, so things aren't really in place for an immediate surge although I am still bullish medium-term," he added.
The U.S. Commerce Department said durable goods orders fell 0.9 percent after an upwardly revised 3.6 percent rise in January. Economists polled by Reuters had expected a 1.1 percent increase after January's rise, which was initially reported at 2.7 percent.
The euro extended gains against the dollar, which helped limit further losses in base metals prices. A weaker dollar makes metals priced in the U.S. currency more affordable for holders of other currencies.
Support also came from data showing U.S. claims for unemployment benefits fell unexpectedly last week.
European premiums for physical copper edged ahead this week, clawing back from two-year lows as traders said demand was perking up and that gains looked set to increase in the traditionally stronger second quarter.
"We could push to a high of $9,850 in this current run, but an advance to $10,000 and beyond looks problematical to us given rising inventory levels and sluggish physical premiums," MF Global said in a note.
Lead CMPB3, which earlier hit a near three-year high at $2,747, ended at $2,690 versus $2,716 at the prior day's close.
Aluminium CMAL3 reversed to close lower after hitting $2,651.00, its highest since September 2008. The metal used in auto parts and packaging finished at $2,630, from $2,631 at the close on Wednesday.
The energy-intensive metal remained supported by brisk demand growth and soaring energy costs.
"If you look at the demand picture for aluminium, it's incredibly positive," said Barclays Capital analyst Gayle Berry.
"And longer-term as well, the question marks over the role of nuclear in the energy mix are certainly helping the back end of the aluminium curve."
The nuclear crisis in Japan is seen lifting power costs as governments rethink energy policies, while conflicts in the Middle East and North Africa have propelled crude oil to 2-1/2-year peaks.
Aluminium inventories remain close to record highs, climbing 14,425 tonnes to 4,608,875 tonnes, data showed on Thursday, although much of the material is tied up in financing deals.
Tin CMSN3 finished at $31,750 from a last bid at $30,925, while zinc CMZN3 closed at $2,421 from $2,424 on Wednesday. Nickel CMNI3 ended at $27,200 from $26,825 a tonne.