North Sea Brent crude, the European benchmark crude contract, was down 3.3 percent at $99.39 a barrel in afternoon trade, while U.S. peer WTI crude was also down 3.3 percent at $96.12.
Prices had fallen on Tuesday after WTI breached the key $100 level on fears that a slowing global economy would dent demand for oil products.
Analysts at Citi predict that Brent could hit $65 later this year if the global economy continues to slump.
Goldman Sachs said on Wednesday that the oil sell-off was driven by growing recession fears.
Oil prices were also hit by a rebound in the dollar, which held at 20-year highs against the euro and multi-month highs against other major currencies.