Oil prices fell on Monday as investors grappled with ongoing concerns over rising U.S. output and tight OPEC supply, while last week's data showing speculators cut bullish bets on oil suggested more selling could be seen.
U.S. West Texas Intermediate (WTI) crude futures finished Monday's session down 68 cents, or 1.1 percent, at $61.36 a barrel. Brent crude futures fell 50 cents to $64.99 per barrel at 2:29 p.m. ET.
Hedge funds and money managers have pared their bullish wagers on U.S. crude oil, with long positions falling last week for the first time in three weeks. Gross short positions — or bets that oil prices will fall — on the New York Mercantile Exchange climbed to their highest level in nearly a month.
That has undercut some of the enthusiasm for oil, as investors weigh increased U.S. supply against the likelihood that the Organization of the Petroleum Exporting Countries and non-OPEC producers will maintain supply cuts that have been in effect for more than a year.
"The market continues to flip back and forth on the idea that increased global demand and a production cut is going to support prices... but U.S. production, and North American production levels in general, is going to negate a lot of the impact of that," said Gene McGillian, director of market research at Tradition Energy.
Crude prices rose on Friday and earlier on Monday after the U.S. economy added the biggest number of jobs in more than 1½ years in February.
In oil markets, U.S. energy companies last week cut oil rigs for the first time in almost two months, with drillers cutting back four rigs, to 796, Baker Hughes energy services firm said on Friday.
Despite the lower rig count, which is an early indicator of future output, activity remains much higher than a year ago when, when just 617 rigs were active. Most analysts expect U.S. crude oil production to expand further. It has already risen by over a fifth since mid-2016 to 10.37 million barrels per day (bpd).
"Permian and Bakken shale basins still saw active oil rigs rising by 2 and 3 last week, respectively, and are likely to keep U.S. oil production on (an) increasing trend," ING said.
The United States has become the world's no. 2 crude oil producer, ahead of top exporter Saudi Arabia. Only Russia pumps more, at nearly 11 million bpd.
The Organization of the Petroleum Exporting Countries (OPEC), together with a group of other producers led by Russia, has been withholding production since the start of 2017 to prop up prices.
It is not clear when the deal to withhold output will end, but Iranian oil minister Bijan Zanganeh said OPEC could agree in June to begin easing current oil production curbs in 2019, the Wall Street Journal reported on Sunday.
This week's Consumer Price Index (CPI) release, given its potential impact on the dollar, could end up being critical, said Bill Baruch, president of Blue Line Futures in Chicago.
The dollar tends to have an inverse relationship with the price of oil, as a weaker greenback makes dollar-denominated commodities cheaper for holders of other currencies.
— CNBC's Tom DiChristopher contributed to this story.