HOUSTON, Dec. 27 (Xinhua) -- The American Petroleum Institute (API) on Thursday reported a build of 6.9 million barrels in the U.S. crude oil inventories for the week ending Dec. 21.

In the previous week ending Dec. 14, API reported a build of 3.45 million barrels.

Oil prices retreated on Thursday, erasing gains in the previous session as concerns over global supply glut and faltering global economy lingered.

The West Texas Intermediate (WTI) for February delivery declined 1.61 U.S. dollars to settle at 44.61 dollars a barrel on the New York Mercantile Exchange, while Brent crude for February delivery decreased 2.31 dollars to close at 52.16 dollars a barrel on the London ICE Futures Exchange.