* Asia shares follow Wall St lower, Nikkei skids 2 pct
* Copper prices melting as Shanghai futures hit lowest since 2009
* Gold jumps to 4-1/2 month high
* Yen edges higher as Australian dollar loses ground
By Wayne Cole
SYDNEY, March 12 (Reuters) - Asian stock markets swung lower on Wednesday as economic uncertainty in China and the United States combined with political tensions in Ukraine to keep investors cautious and commodities under a dark cloud.
Copper grabbed the headlines as Shanghai futures fell 5 percent to their lowest since 2009 amid concerns about the potential unravelling of loan deals where the industrial metal has been used as collateral.
Japan’s Nikkei retreated 2 percent, continuing the see-saw pattern of the last couple of months, while Australian stocks shed 1 percent. MSCI’s broadest index of Asia-Pacific shares outside Japan fell 1 percent.
That mirrored a lacklustre performance by Wall Street, where soft data left investors no wiser on whether the economy’s troubles were merely weather-related or something more fundamental.
The Dow ended Tuesday down 0.41 percent, while the S&P 500 lost 0.51 percent.
Lurking in the background was the standoff in Ukraine. Ukraine’s acting president announced the formation of a volunteer national guard, while ousted leader Viktor Yanukovich insisted he remained the legitimate leader.
In Asia, investors are hoping Chinese data on industrial output, retail sales and urban investment due on Thursday might offer some clarity on where the economy is heading.
In the meantime, caution was the watchword as concerns about the state of Chinese demand continued to pressure industrial commodities, particularly copper and iron ore.
Both metals have been used in China as collateral for loans, leaving traders and steel mills vulnerable to a credit squeeze.
“Copper prices continue to slide on concerns that the cyclical metal may face tough times as China slows and rebalances away from investment into consumption,” said analysts from Barclays in a note.
At least one U.S. scrap copper trader has suffered “large” losses after a buyer in China defaulted on a deal in the past week, one of the first signs that sinking prices and tightening credit are taking a toll on the physical market.
“Global risk sentiment has held up well, however, as so far the market does not seem to identify these risks as systemic,” noted Barclays.
The relative calm was clear in the U.S. Treasury market, where yields on 10-year notes have hovered around 2.77 percent for the past couple of sessions.
Supporting sentiment was a Reuters report that China’s central bank is prepared to loosen monetary policy if economic growth slows further by cutting the amount of cash that banks must keep as reserves.
Citing sources involved in internal policy discussions, the report said an easing would be triggered if growth slips below 7.5 percent, and would come on top of money market operations and currency intervention via state banks that traders say has already loosened monetary conditions overall.
The slide in prices for copper and iron ore undermined Australia’s dollar as the country is a major exporter of both metals. The currency was down at $0.8952 on Wednesday, having shed half a U.S. cent overnight.
It was one of the few movers among the major currencies, which have been trading in tight ranges recently. The dollar eased a touch on the yen to 102.91 as the Japanese currency benefited from its traditional status as a safe haven.
The euro edged lower to $1.3855 after officials from the European Central Bank reminded investors there was still scope to ease policy if needed.
One beneficiary of global uncertainty has been gold, which jumped in Asian trade on Wednesday to a 4-1/2 month high of $1,359.25 an ounce.
Oil prices extended their pullback with Brent crude off 29 cents to $108.26 a barrel, while U.S. oil lost 55 cents to $99.48.