Global oil prices tumbled Thursday, sending U.S. crude prices below $60 a barrel, as a bigger-than-expected buildup in domestic stockpiles and increasing concern over the health of the world economy.

Investors have been dumping oil holdings for most of the week, in fact, sparking the biggest five-day slide in six months that was accelerated by data from the Energy Information Administration yesterday which showed U.S. crude stockpiles rose by a larger-than-expected 4.7 million barrels last week to 476.8 million barrels, the highest in nearly two years.

Brent crude contracts for July delivery, the global benchmark for oil prices, were marked $3.65 lower from their Wednesday close in New York and changing hands at $67.34 per barrel while WTI contracts for the same month were seen $3.55 lower at $57.87 per barrel.

The Energy Select Sector SPDR ETF (XLE) - Get Report was marked 3.5% lower at $61.31 per unit, a move that extends its one-month decline to just over 10.5%

The sell-off was also sparked by weaker-than-expected economic activity data from both Europe and the United States today, with the May PMI reading for the world's biggest economy's manufacturing sector slowing to its weakest pace in a decade.

"Growth of business activity slowed sharply in May as trade war worries and increased uncertainty dealt a further blow to order book growth and business confidence," said IHS Markit's chief economist.

The reading echoed weakness in Europe, as well, where Germany's manufacturing sector showed further signs of a deepening contraction and business morale, as measured by the closely-watched Ifo Index, sank to a November 2014 trough.