Barely a week after appearing like they'd won the market back, oil bulls were at a loss again on Thursday as crude prices tumbled for a third-straight day on concerns that sanctioned Iranian supplies might come roaring back.

New York-traded West Texas Intermediate crude, the U.S. benchmark blend, settled down 66 cents, or 1.2%, at $55.09 per barrel as OPEC's vow to balance the market with supply cuts were trumped by fears there might be a resolution soon to the near year-long U.S. embargo on Iranian crude. WTI fell as much as $1.73 earlier, before pulling back some of its losses late bargain-hunting activity.

London-traded Brent crude, the international benchmark blend, settled down 43 cents, or 0.7%, at $60.38 per barrel. Brent tumbled as much as $1.90 earlier.

Both WTI and Brent have lost about 4% or more since Tuesday after the White House announced that U,S. National Security Advisor John Bolton, a long-time hawk on Iran, had left the Trump administration. Prior to that, the two benchmarks had gained about 7% each over a four-day rally helped by optimism about outsize weekly U.S. crude draws.

Source : Investing.com