By Glenys Sim April 5 (Bloomberg) -- Copper jumped to a 20-month high in New York after global manufacturing expanded and inventories declined, signaling demand is improving. Copper for May delivery on the Comex in New York rose as much as 1.1 percent to $3.6235 a pound, the highest level since Aug. 1, 2008, before trading at $3.621 at 9:58 a.m. in Singapore. Futures resumed trading today after the exchange closed on April 2 for the Good Friday holiday. Markets in London and Shanghai are closed today. Futures also climbed as the dollar weakened 0.3 percent against a basket of six currencies, boosting the appeal of commodities as alternative investments. Copper surged 5.3 percent in New York last week as the Dollar Index fell 0.5 percent. “Sentiment is still pretty positive following the robust performance after last week’s data,” Yingxi Yu, an analyst at Barclays Capital, said from Singapore today. Trading may be thin this week as investors and mining company executives meet at metals conferences in Santiago, including a dinner organized by a Chilean research group known as Cesco, or the Center for Copper and Mining Studies. “Volumes this week will probably be low, with many people out at Cesco, and we’ll probably get some direction from what people are talking about at the conference,” Yu said. Copper for three-month delivery on the London Metal Exchange gained to a 20-month high of $7,939.75 a metric ton on April 1, after reports showed manufacturing expanded in China, India, the U.S. and Europe. The metal used in construction and automobiles also advanced after Shanghai copper stockpiles fell for a second week and LME-tracked inventories slid for a 22nd straight session. To contact the reporter for this story: Glenys Sim in Singapore at gsim4@bloomberg.net

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