* Rebar, iron ore futures fall 6 pct before trading limits come in
* Economic worries combine with seasonal demand slowdown for steel
* Metals and some agriculture contracts also follow
* Dalian exchange vows to keep curbing speculation
By Ruby Lian and Gavin Maguire
SHANGHAI/SINGAPORE, May 9 (Reuters) - Chinese commodities futures fell almost across the board on Monday, led by 6 percent drops in steel and iron ore futures, as worries about waning demand in the world's top consumer of most industrial materials extended last week's slide.
Speculative funds had rushed into China's commodities futures last month, betting that the country's economy was bottoming out, alarming exchanges and regulators who feared a new bubble was forming as volumes and prices soared.
China's three commodity exchanges have taken a string of aggressive measures, including raising trading margins, daily movement limits and transaction fees in a bit to limit speculation and cut trading volumes of futures from steel to eggs.
The Dalian Commodity Exchange said on Monday it would continue to strengthen its market monitoring and may raise transaction fees further to curb risks from speculation. liquidity has dropped sharply following exchanges' measures and now investors are worried that China's economic trend will be weaker than previously expected, hurting sentiment," said Zhao Chaoyue, an analyst at Merchant Futures in Shenzhen.
The most-traded rebar on the Shanghai Futures Exchange SRBcv1 posted its biggest daily fall on record on Monday, hitting a downside limit of 6 percent to 2,175 yuan ($334.41) a tonne, the lowest since April 7.
September iron ore futures on the Dalian Commodity Exchange DCIOcv1 also tumbled by their daily permissible limit of 6 percent to 388 yuan a tonne.
Chinese customs data issued on Sunday showed that iron ore imports fell 2.2 percent from March to 83.92 million tonnes, while copper ore and concentrate imports shed 8 percent on the month to 1.26 million tonnes. economic trend will be "L-shaped", rather than "U-shaped", and definitely not "V-shaped", as structural reforms take time, while the government will not use excessive investment and credit to stimulate growth, the government-owned People's Daily reported on Monday. the weekend, spot prices of billet, a semi-finished steel product, which is considered as a key reference for the physical market, tumbled 130 yuan to 2,130 yuan a tonne, traders said.
"Steel demand is seasonally weaker between June and August, while output keeps rising, which has been interpreted by investors as the turning point of the economic recovery," said Zhao, who remains positive that the economy will still improve from last year.
Other steelmaking raw material futures also fell, with metallurgical coke DCJcv1 slumping 6.3 percent to 936 yuan a tonne and coking coal DJMcv1 shedding 5.6 percent to 655.5 yuan by 0306 GMT. Nickel SNIcv1 dropped 2.7 percent to 69,520 yuan a tonne.
The selling also hit agricultural futures.
China's Dalian soybeans DSAcv1 slid for a fourth consecutive session on Monday to their lowest in nearly three weeks even as strong demand from the world's top importer of the commodity drove the benchmark U.S. prices Sv1 higher.
Cotton futures CCFcv1 on Zhengzhou Commodity Exchange lost 3.1 percent to trade at their lowest since April 18.
Rubber futures SNRcv1 fell more than 4 percent to 11,745 yuan a tonne. ($1 = 6.5039 Chinese yuan renminbi)