MELBOURNE, April 12 (Reuters) - London zinc fell to a four-month low on Thursday, tracking the prices of other steel materials as demand from construction got off to a slow start in the usually strong second quarter. FUNDAMENTALS * London Metal Exchange zinc slid 2.7 percent to $3,150 a tonne by 0244 GMT, having earlier touched a low of $3,133.50, its weakest since Dec. 12. Prices crashed through support at the 200-day moving average of $3,172 a tonne, triggering a rush in sales from funds, a trader said. * LME copper fell 0.8 percent to $6,893 a tonne reflecting a sour tone across metals amid broad risk-off sentiment in the markets. Shanghai Futures Exchange copper fell 1 percent to 50,610 yuan ($8,063.40) a tonne. * STEEL DEMAND: Iron ore futures in China have been falling, with investors worried about slipping steel margins this year and leaner demand in the world's top consumer. A seasonal pickup in China's construction activity that usually comes in April and May has been off to a slow start, traders said. * ZINC: Longer term, zinc prices are expected to remain buoyant after hitting their highest in a decade because of years of underinvestment, the founder and chairman of Vedanta Resources said on Wednesday. * CHINA POLLUTION: The Chinese city of Xuzhou is carrying out environmental inspections targeting air pollution emissions at industrial plants, construction sites and in the transport sector that are expected to last for as long as six months. * RUSAL: International financial groups took action on Wednesday to distance themselves from the shares, bonds and metal of Russian aluminium giant Rusal after the United States imposed sanctions on the company. ] * CME Group has also revoked approved status for registration of Russian firm Rusal's metal for delivery against its aluminium futures contracts, according to a notice on its website. * GLENCORE: Trader Glencore, a Rusal shareholder and customer, will declare force majeure on some aluminium supply, a source familiar with the matter said.