Aug 31, 2011 NEW YORK (Dow Jones)--Copper futures are sweeping higher amid quiet trade as investors focus on better physical demand from China and concerns about supply.

The most actively traded contract, for December delivery, was recently up 5.25 cents, or 1.3%, at $4.1940 a pound on the Comex division of the New York Mercantile Exchange.

The front-month contract, for September delivery, was up 5.35 cents, or 1.3%, at $4.1765 a pound.

Chinese appetite for physical copper has perked up as buyers there take advantage of recently lower prices to restock supply. The stronger demand has pushed the price of copper traded on the Shanghai Futures Exchange above that traded on the London Metal Exchange, drawing copper stocks stored at LME warehouses in South East Asia to China.

"Evidence of Chinese buying has reminded the market that the fundamental backdrop for many of the metals is positive and that the fear-induced sell-off was not reflective of any sudden change in the fundamentals," said Gayle Berry, a base metals analyst with Barclays Capital.

Goldman Sachs said it remains "very bullish on copper fundamentals" as problems with copper mine output will reduce the amount of metal available to the market by more than previously expected.

"Copper supply disruptions will amount to at least 8% of total production loss this year, compared to 4%-5% we had expected earlier in the year," Goldman said.

Copper trading volumes remain low as the final week of August draws to a close. Many copper traders in Europe are taking time off for the final week of summer while in the U.S. investors are often away for the week before Labor Day.

Red metal prices climbed higher despite a report showing private businesses in the U.S. added a modest 91,000 new jobs in August, according to payroll giant Automatic Data Processing Inc. (ADP) and consultancy Macroeconomic Advisors. Economists had expected a gain of 100,000.

Copper traders are more concerned with the government's non-farm payrolls data, which is due out Friday morning and is forecast to show a gain of 80,000 new jobs.