* Dalian iron ore, coking coal, coke slump by 6 pct limit
* Dalian bourse raised transaction fees twice this week
* Shanghai rebar down nearly 5 pct
By Manolo Serapio Jr
MANILA, April 27 (Reuters) - Iron ore and steel futures in China sank again on Wednesday as authorities raised trading costs to deter speculative investors believed to be behind last week's big spike in prices and volumes, which has raised fears of a destabilising crash.
The Dalian Commodity Exchange increased the transaction fees on steelmaking raw materials iron ore, coking coal and coke for a second time this week. Other commodity exchanges in Shanghai and Zhengzhou have imposed similar curbs to restore calm in markets after a week-long surge unsettled global investors.
"I think it's working," said Wang Di, analyst at CRU consultancy in Beijing, referring to the trading curbs. "What they're trying to do is minimise too much speculation, especially from the retail investors."
Analysts say speculators were betting that a rise in infrastructure spending in China would lift raw material prices, which have been depressed for years by a persistent supply glut.
The rapid price gains have defied the supply-demand fundamentals of the commodities, and analysts warn there is a risk of a bigger correction ahead, similar to last summer's crash in Chinese shares, which also followed a frothy run-up.
"If prices in China go too far off from fundamentals, markets in China could lose credibility, similar to what had happened in the stock market," Citigroup (NYSE:C) analysts said in a report.
The most traded September iron ore on the Dalian Commodity Exchange DCIOcv1 dropped by its 6 percent downside limit for a second day in a row on Wednesday, and was standing at 432 yuan a tonne by midday.
Coking coal DJMU6 and coke DCJU6 on Dalian also slid by the 6 percent maximum allowed by the exchange.
On the Shanghai Futures Exchange, rebar - or reinforcing bar used in construction - fell 4.8 percent to 2,472 yuan a tonne SRBcv1 . The less-traded hot rolled SHHCV6 tumbled by its 6 percent downside limit.
After raising the transaction fee on iron ore futures contracts twice, the Dalian exchange said it "will step up supervision and resolutely curb signs of overheated speculation in some products to prevent risks and maintain steady operations of markets".
The bourse said it would be on high alert in monitoring market movements and will take more measures if necessary, according to a statement from the exchange issued late on Tuesday.
Wednesday's pullback was largely limited to steel and steelmaking futures, but other commodities also slipped. Cotton on the Zhengzhou Commodity Exchange CCFU6 fell 2.5 percent, and egg futures slipped nearly 2 percent on Dalian DJDU6 .
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http://tmsnrt.rs/1VUmj8V
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