Base metals close lower on the LME COPPER futures have closed lower on the close of London Metal Exchange (LME), weighed down by concern about the oversupply of metal to the market and a lack of appetite for trading ahead of the US Thanksgiving holiday. At the PM kerb close on Tuesday, LME three-month copper was down 0.5 per cent at $US7,065 a metric ton. Aluminium was 0.1 per cent lower at $US1,773 a ton. "Although we are seeing periodic rallies, most (base metals) are unable to sustain themselves given the backdrop of chronic surpluses," said INTL FCStone analyst Edward Meir. According to the International Copper Study Group, the global refined copper market was in oversupply by 21,000 metric tons in August, its first surplus in four months. Analysts said demand in China, the world's top consumer of the industrial metal, remains in flux, with power-grid investments declining in October for the second month in a row, while imports of refined metal increased 27 per cent from a year ago as some traders bought the metal to use it as collateral for short-term loans. Base metal trade was thin Tuesday as traders avoided placing bold bets before a US public holiday later in the week. "Ahead of the US Thanksgiving holiday on Thursday, the base metals markets have been quiet, with participants happy to sit on the sidelines," said Standard Bank analyst Leon Westgate. As a consequence, turnover has been pretty subdued, while prices have also tended to edge sideways with the metals trading in fairly limited intraday ranges.