Oil markets lost momentum on Tuesday, as economic prospects and US production surged, overshadowing the impact of expected cuts in OPEC supplies.
Brent crude was $ 66.43 a barrel at 06:08 GMT, down 36 cents, or 0.5 percent below last closing.
US WTI fell to $ 56.97 a barrel, down 23 cents, or 0.4 percent, from the latest settlement.
The declines came after price increases earlier in the session.
Oil prices have fallen nearly a quarter of their recent highs, recorded in early October as a result of increased supplies, particularly from the United States.
US production has risen about 25 percent this year, hitting a record 11.7 million bpd.
This comes amid widespread expectations of an economic slowdown, pushing Asian stocks down Tuesday as well as sharp losses on Wall Street yesterday.
Concerned that the output surplus, which began to show prices collapse, as in 2014, OPEC is pushing for a supply cut of between 1.4 million and 1.4 million bpd.
