BEIJING, March 28 (Reuters) - London copper gave up early gains to trade lower on Wednesday, tracking a decline in equities on a firmer U.S. dollar and as global trade tensions persisted. The dollar index, which gained about 0.3 percent overnight, making metals more expensive for holders of other currencies and weighing on prices, was trading up 0.2 percent by 0722 GMT. Fears of a trade war between the United States and top metals consumer China continued to cast a shadow over the base metals market, even as reports of behind-the-scenes talks between Washington and Beijing spurred some optimism. Base metals are showing less volatility amid thin trade end as the end of the quarter approaches. "Overall it has been a much more sedate session so far today both in terms of absolute volumes and ranges with many traders staying away from the base metal noise for now," broker Marex Spectron said in a note. FUNDAMENTALS * LME COPPER: Three-month copper on the London Metal Exchange (LME) was down 0.6 percent at $6,607 a tonne by 0724 GMT, having risen as much as 0.4 percent earlier in the session. * SHFE COPPER: The most-traded May copper contract on the Shanghai Futures Exchange closed down 0.4 percent at 49,260 yuan ($7,846.45) a tonne. * OTHER METALS: All other base metals were down with the exception of Shanghai lead, which closed up 0.6 percent at 18,645 yuan a tonne. * COPPER: Vedanta Resources Plc said on Tuesday its India unit Vedanta Ltd's copper smelting operations at Thootukudi, in the southern state of Tamil Nadu, will be closed for about 15 days as part of a maintenance shutdown. * ALUMINIUM: China's northern province of Shanxi on Tuesday offered some of the country's biggest aluminium companies preferential access to bauxite resources if they transfer smelting capacity to the region. * ALUMINA: The Alunorte refinery in northern Brazil, owned by Norway's Norsk Hydro ASA, will start shutting down half of its alumina capacity in the next two weeks to preserve equipment, two people familiar with the matter said on Tuesday.