US benchmark West Texas Intermediate (WTI) for October delivery dropped USD 2.21 to USD 38.24 a barrel on the New York Mercantile Exchange, its first below-USD 40 close since February 2009.
Brent North Sea crude for October, the international benchmark, plummeted USD 2.80 to USD 42.69 a barrel in London, its lowest level since March 2009.
"The petroleum markets are extending last week's decline along with global equity markets today as worries over slowing Chinese economic growth intensified," said Tim Evans, energy markets strategist at Ciri Futures.
The catalyst was the Shanghai stock market's 8.5 per cent plunge, its sharpest one-day fall in eight years, despite Chinese government efforts to stem market turmoil on markets since mid-June.
More From This Section
"These jitters over China -- if you think they're bad for the US equity market, they're even worse for the global oil market," said John Killduff of Again Capital.
He estimated that the WTI contract had further to fall. "I thought we'd be getting into the mid-USD 30s. Now I think we'll be getting into the mid-USD 20s," he said.
Bart Melek, head of commodity strategy at TD Securities, said the oil market was getting clobbered from two sides: The outlook for demand was weakened by China's woes and there was no sign of easing in the global oversupply.