BEIJING, Aug 21 (Reuters) - Base metals prices rose on Tuesday, with London copper climbing for a second day and crossing the $6,000-a-tonne mark as the dollar slipped, while the market awaited U.S.-China trade talks in Washington. Copper prices on the London Metal Exchange have fallen by 18 percent from a four-year high touched on June 7 amid concerns a trade row between the United States and China, which have slapped billions of dollars in tariffs on each other's goods, will hit demand for industrial metals. But Jefferies analyst Timothy Ward wrote in a note that the "pendulum may have swung too far too fast." "Sentiment and positioning have shifted so strongly from these macro forces that the underlying copper story may have been thrown out with the bath water," he said, adding that the last time speculative positioning had so many shorts and so few longs, copper rallied 19 percent over the next three months. FUNDAMENTALS * LME COPPER: Three-month copper on the LME rose as much as 0.9 percent to a one-week high of $6,046.50 a tonne and was trading up 0.7 percent at $6,037 a tonne by 0705 GMT. * SHFE COPPER: The most-traded October copper contract on the Shanghai Futures Exchange closed up 1.3 percent to 48,700 yuan ($7,084.67) a tonne after hitting its highest since Aug. 15. * USD: The dollar index against a basket of six other currencies fell 0.3 percent to 95.583 after touching 95.440, its lowest level since Aug. 9. A weaker greenback makes metals cheaper for holders of other currencies and can support prices. * VEDANTA: India's environment court said on Monday an independent judicial committee would decide in about six weeks whether to allow Vedanta Ltd to reopen its copper smelter, which was shut by the southern state of Tamil Nadu on environmental grounds. * OTHER METALS: Zinc was the star performer, closing up 3.1 percent in Shanghai after breaking through its 7-day moving average, and added 2.2 percent in London. Shanghai aluminium jumped 2 percent and nickel rose 1.2 percent, while tin was the sole laggard, losing 0.3 percent.