Copper rallied about 2 percent on Friday after the US job data boosted confidence in the recovery of the world's largest economy and as Greece's success with a debt swap deal eased fears about the euro zone debt crisis. But investors were wary about large copper stockpiles that have accumulated in Shanghai warehouses, where stocks rose to 224,781 tonnes last week, their highest level since July 2002. Weekend data showing a slowdown in China's exports in February heightened concerns that global demand is still weak, while data out earlier showing that Italy was in recession undermined relief over the Greek debt swap. Three-month copper on the London Metal Exchange ended at $8,445 a tonne, down from $8,490 on Friday, handing back some of the gains made over the course of a three-day rally. "Markets are still struggling for real conviction over (price) direction. In copper especially the market seems to still be focused on the demand side of the story, so slower growth in China etc.," said Macquarie analyst Duncan Hobbs. China's copper imports remained surprisingly strong in February, with inflows of the industrial metal up 17 percent from January and double a year earlier. But many analysts fear the metal is piling up in warehouses, rather than being consumed. Data out on Friday showed copper output in both January and February hit its lowest since the first quarter of 2011 as demand for the metal was blunted by slower economic activity. "We had slower GDP growth and slower copper consumption growth in China this year, but we continue to expect the authorities are certainly going to do as much as they can to prevent a sharp downturn," said Caroline Bain, economist at the Economist Intelligence Unit. Also weighing on prices was a strong dollar, which makes commodities priced in the US unit more expensive for holders of other currencies. The dollar remained near its highest level in nearly a month against the euro. The single currency is expected to struggle in the coming weeks as relief at Greece's debt restructuring gives way to concerns about euro zone growth and risk of contagion. PEAK SEASON "Theoretically we are in the peak consumption season, but it doesn't feel like it this year," a Shanghai-based physical copper trader said. "Factories are not in any rush to stockpile the material as the overall economic situation has weakened." China, which consumes about 40 percent of the world's copper, has cut its 2012 growth target to an eight-year low of 7.5 percent, dampening hopes that its appetite for these materials would continue to expand rapidly. "For prices to rise on a sustained basis, more signs of firming Chinese demand are needed, in our view. We believe that near-term trading conditions are likely to remain choppy," said Credit Suisse analysts in a note. Money managers, including hedge funds and other large speculators, reduced their net length in US copper futures and options by 2,003 lots to 13,615 lots in the week ended March 6. Attention is now turning to Tuesday's US Federal Reserve policy meeting, which will look at whether the current programme of monetary stimulus, due to expire in late June, needs to be extended or altered. Copper has gained around 11 percent this year due to relief that Europe's debt crisis did not escalate as feared, though the outlook going forward is more murky, with fears over an end to central bank policy easing and weak eurozone growth. Three-month aluminium fell to $2,229 a tonne from Friday's close of $2,240, extending a 3.8-percent slide in the previous week - its biggest weekly drop since the end of November. Latest data showed LME stocks fell 2,600 tonnes, though remained near record levels at 5.01 million tonnes, with most of the metal locked up in financing deals and unavailable to the market. LME tin closed at $23,475 a tonne from $23,200. Prices gained nearly 20 percent so far this year, leading the industrial metals complex. The outlook for tin going forward is shaky though, especially amid latest news that refined exports from Indonesia, the world's top exporter, soared 35 percent on the year to 8,324.73 tonnes in February. Zinc, used in galvanizing, closed at $2,091 a tonne from $2,070, battery material lead ended at $2,138 from $2,120, while stainless-steel ingredient nickel closed at $19,260 from $19,300.