* Escondida annual copper output soars 28 pct to 1.1 mln tonnes * US Senate to hold hearing on banks owning commodities storage * Coming Up: Fed Chairman testifies at 1400 GMT By Maytaal Angel LONDON, June 17 (Reuters) - Copper slipped from near a one-month high on Wednesday as the dollar steadied and traders grew nervous ahead of Federal Reserve Chairman Ben Bernanke testimony on monetary policy to Congress later today. Bernanke is expected to use his testimony to calm market worries about life without the central bank's $85-billion-a-month bond-buying programme. But base metals markets are nervous all the same, with the dollar recouping some of the previous sessions losses versus a currency basket, and with news of an sharp increase in supplies at the world's biggest copper mine. A stronger dollar makes metal priced in the greenback more costly for European and other non-U.S. investors. Three-month copper on the London Metal Exchange climbed as high as $7,046 a tonne on Wednesday, within reach of a near one month high hit July 11, before slipping to $6,925 a tonne by 0939 GMT, down 1.04 percent. Copper prices have failed to find momentum above $7,000 a tonne, though they rose to those heights earlier this month after comments favouring looser U.S. monetary policy for longer triggered a cross-commodity rally. "There's a bit of trepidation ahead of the Fed but (overall) the investor community is short copper. With a more dovish tone from the Fed we could see a bit more of that short covering," said Credit Suisse analyst Tom Kendall. "But once you get through the summer period, we are still bearish on copper and expect to see additional supply coming through at a faster pace than demand can absorb." BHP Billiton, majority owner of Escondida in Chile, the world's single-largest copper mine, said earlier copper output rose 28 percent to 1.1 million tonnes in the 2013 fiscal year. The news added to expectations that the copper market will in 2013 record a surplus for the first time in three years. Adding support to prices, however, China's consumption of refined copper is likely to rise in the second half, buoyed by expected government backing for power sector investments to support economic growth. China is the world's largest copper consumer, accounting for about 40 percent of demand. Its economic growth slowed to 7.5 percent in the second quarter, from 7.7 percent in the first quarter, leaving a big dent in copper prices, which are down nearly 13 percent this year. China's commerce ministry said on Wednesday that it will soon release measures to support exports and imports, though it did not give details. Elsewhere, the U.S. Senate committee will hold a hearing on whether banks should control physical commodities storage, a practice that detractors argue has resulted in long queues to get metals out of LME warehouses. The queues have prompted rising spot premiums on the physical markets, and have also spurred producers to crank up output in spite of falling demand, weighing on LME benchmark prices. In other metals traded, zinc fell 1.09 percent to $1,867.50 a tonne, with latest daily LME stocks data showing a massive 75,900 tonne increase in inventories to 1.077 million tonnes, near their highest level in over a month. Metal Prices at 0936 GMT Comex copper in cents/lb, LME prices in $/T and SHFE prices in yuan/T Metal Last Change Pct Move End 2012 Ytd Pct move COMEX Cu 3.14 -0.04 -1.40 365.25 -99.14 LME Alum 1810.50 -4.50 -0.25 2073.00 -12.66 LME Cu 6925.25 -72.75 -1.04 7931.00 -12.68 LME Lead 2054.25 -20.75 -1.00 2330.00 -11.83 LME Nickel 13764.00 -6.00 -0.04 17060.00 -19.32 LME Tin 19411.00 -44.00 -0.23 23400.00 -17.05 LME Zinc 1865.75 -22.25 -1.18 2080.00 -10.30 SHFE Alu 14310.00 0.00 +0.00 15435.00 -7.29 SHFE Cu* 50050.00 -110.00 -0.22 57690.00 -13.24 SHFE Zin 14635.00 -45.00 -0.31 15625.00 -6.34 ** Benchmark month for COMEX copper * 3rd contract month for SHFE AL, CU and ZN SHFE ZN began trading on 26/3/07

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