* CSI300 -2.6 pct; SSEC -2.9 pct; HSI -0.6 pct
* Energy, resource shares drop on lower oil, commodity prices
* China shares poised to end their six-day rising streak
Chinese benchmark indexes were poised to end their six-session winning streak, with the blue-chip CSI300 index falling 2.6 percent to 3,025.66 points by lunch break, and the Shanghai Composite Index shedding 2.9 percent, to 2,817.21 points.
In Hong Kong, the Hang Seng index was off 0.6 percent, while the Hong Kong China Enterprises Index was down 1.7 percent.
China and Hong Kong equities had joined other Asian markets in a robust rebound over the past month, aided by recovering oil and commodity prices, and receding concerns over the global economy.
But the rally could be petering out, as a renewed slump in raw material prices and ugly China trade data revive growth anxieties.
"Investors are rushing out of stocks today as they anticipate a well-deserved correction following the overnight tumble in global commodity prices," said Cao Xuefeng, a strategist at Huaxi Securities.
Shares of resource businesses tumbled roughly 6 percent in China and nearly 5 percent in Hong Kong, while an index tracking nonferrous metals prices in Shanghai also dropped sharply.
Investors are growing increasingly concerned the recent bounce in prices of steel, copper and other commodities is not justified, given persistent Chinese economic weakness - as evidenced by the country's much worse-than-expected February trade data.
China's supply-side reforms - which aim at reducing industrial over-capacity - only provide momentary stimulus for cyclical stocks, but forms no basis for a longer-term trend, wrote Zhu Bin, an analyst at Southwest Securities.
Further reducing market expectations of massive stimulus by the government, a senior researcher of China's cabinet told reporters on Wednesday that China's wider fiscal deficit budgeted for 2016 will be mainly used to finance tax cuts.
The energy sector also slumped, losing 5.5 percent in China and 3.2 percent in Hong Kong, after a correction in oil prices. - Reuters