Crude oil prices fluctuated with rising supply risks in the Middle East and surprise inventory buildup in the U.S. for the week ending June 14.
International benchmark Brent crude was trading around $61.39 per barrel at 1150 GMT on Friday, heading for 3.44% weekly loss, after it opened Monday at $63.58 a barrel.
American benchmark West Texas Intermediate (WTI) was at $54.24 a barrel at the same time for a 3.87% weekly decline, after it started the week at $52.14 per barrel.
Brent crude lost more than 3.7% on Wednesday, while WTI decreased 4% when crude oil inventories in the U.S. increased surprisingly despite the market expectation of a decline.
Commercial crude oil inventories in the U.S. increased by 2.2 million barrels for the week ending June 7, according to data released by the Energy Information Administration (EIA). The market expectation for the inventories was a decline of 0.5 million barrels.
The EIA data also revealed that U.S. crude oil production remained near the record high level of 12.3 million bpd (mbpd) for the week ending June 7, signaling that glut of supply in the global oil market is to remain strong until the second half of 2019.
However, both Brent crude and WTI posted 2.23% increase on Thursday after two oil tankers were attacked in the Gulf of Oman.
The attacks, which came after a month when four tankers were attacked in the region, intensified worries amid secure supply of oil from the world's largest oil transport chokepoint -- the Strait of Hormuz.
The global oil market awaits the meeting between OPEC and its allies, which include Russia, that will take place at the end of this month, hoping that the group dubbed as OPEC+ would continue implementing their production cut deal, or lower their output further, in the second half of the year to support prices.
By Ovunc Kutlu