Oil prices fell about 2 percent on Tuesday on forecasts for rising U.S. crude output and a gloomier outlook for global demand growth in a report from the International Energy Agency.
Analysts also noted that oil prices were being pressured by a global commodities selloff, led by base metals like nickel and copper, due to weaker-than-expected economic data from China.
U.S. West Texas Intermediate (WTI) crude ended Tuesday's session down $1.06, or 1.9 percent, to $55.70, posting its worst daily performance since Oct. 6. The contract plunged to $55.18 at the session low.
Brent crude futures fell $1.04, or 1.7 percent, to $62.12 per barrel by 2:26 p.m. ET (1826 GMT), after falling as low as $61.36 earlier in the session.
U.S. crude intraday performance
Market watchers said the declines caused some short-term traders to get nervous and sell out of their positions. Traders noted that Brent slid more after the contract fell below its 14-day moving average for the first time in three weeks.
Just last week, prices for both benchmarks hit their highest levels since 2015.
The IEA delivered a surprisingly downbeat outlook for oil demand in its monthly market report, showing an expected slowdown in consumption that was at odds with a more bullish view from the producer group OPEC on Monday.
The Paris-based IEA cut its oil demand growth forecast by 100,000 barrels per day (bpd) for this year and next, to an estimated 1.5 million bpd in 2017 and 1.3 million bpd in 2018.
The IEA said warmer temperatures could reduce consumption, while sharply rising output from some producer countries might bring back the global crude glut in the first half of 2018.
"The IEA slashing its oil demand growth forecast for this year and the next has dampened some of the bullish sentiment prevailing in the market," Abhishek Kumar, Senior Energy Analyst at Interfax Energys Global Gas Analytics in London.
IEA's report conflicted with OPEC's forecast issued on Monday. OPEC raised it demand outlook by 130,000 bpd from its previous estimate. It now expects oil demand to rise by 1.51 million bpd next year.
The difference in the two reports is being compounded by the lack of tumult in the Middle East, said John Kilduff, founding partner at energy hedge fund Again Capital. Oil prices rose last week on concerns about rising tension between regional powers Iran and Saudi Arabia, as well as uncertainty about the Saudi crown prince's political purge.
"That all that got fed into prices last week and nothing is happening. The risk premium gods giveth and they taketh away," he told CNBC.
This sentiment comes in part on the back of rising U.S. oil output, which has grown by more than 14 percent since mid-2016 to a record 9.62 million bpd.
The U.S. government said on Monday U.S. shale production in December would rise for a 12th consecutive month, increasing by 80,000 bpd.
"The recent price support, namely the tension in the Middle East, has been swept aside as rising rig counts and U.S. shale output (are) in the focus of traders," PVM Oil Associates analyst Tamas Varga said.
Despite the cautious sentiment, traders said oil prices were unlikely to fall far, largely due to supply restrictions led by the Organization of the Petroleum Exporting Countries and Russia, which have helped reduce excess stockpiles.
— CNBC's Tom DiChristopher contributed to this report.