Oil prices tumbled more than 5 percent on Monday as markets worried about a China-led global economic slowdown that would drastically hit oil consumption at a time of plentiful supply.
U.S. light crude closed down $2.21, or 5.5 percent, at $38.24 a barrel, which was the lowest since February 2009. Steep losses last week capped the contract's longest weekly losing streak since 1986.
Brent crude was trading down $2.70, or about 6 percent, at $42.80 a barrel, after hitting a session low of $42.51, its weakest since March 11, 2009.
Chinese stock markets suffered their biggest one-day drop since the financial crisis, stirring huge sell-offs in global equities and commodities, with more than 400 billion euros ($465 billion) wiped off FTSEurofirst 300 index.
"Today's falls are not about oil market fundamentals. It's all about China," Carsten Fritsch, senior oil analyst at Commerzbank in Frankfurt, told Reuters Global Oil Forum. "The fear is of a hard landing and that things get out of the control of the Chinese authorities."