August contracts fell to as low as $102.19, a level not seen since July 1, 2013.
"The petroleum markets have tipped back to the downside, with the Brent market fully refunding Wednesday's gains, after Euro Zone GDP data was weaker than expected, including a 0.2% decline for Germany in the first contraction since 2012," Citi's Timothy Evans said in a note.
He pointed out that the data predate new Russia sanctions that could yet further weigh on output going forward.
Earlier this week, the International Energy Agency said Europe oil demand growth would be flat for the next two years.
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