There is concern among China's leadership that rising global metal prices are spurring rapid investment in mines that could have devastating environmental consequences, AFP reported, citing state media. Smaller mines are a particular worry as market entry barriers are so low, permitting companies with backward technology and poor management to get involved. As a result, the government plans to increase monitoring in traditional mining strongholds such as the Xinjiang region in the northwest and the middle and lower reaches of the Yangtze River basin. There is also talk of tripling the resource tax imposed on coal mining companies to 3%, although no indication has been given as to when this measure might be introduced. The cost of nickel, which is used to produce stainless steel, has risen threefold in the last year while copper, lead, tin and zinc prices are all nearing record highs.