Oil prices fell about 3 percent on Friday, as a week of profit-taking and the return of oversupply concerns led the market lower, snapping a multi-week bull run.
U.S. West Texas Intermediate (WTI) crude fell 2.95 percent, settling at $49.29, breaking a four week win streak. It closed down nearly 4.5 percent in the worst performing week since March 10.
The prospect of extended oil production cuts by the Organization of the Petroleum Exporting Countries and other producers led by Russia had supported prices on Thursday.
But on Friday Russia clarified remarks on the oil market made by President Vladimir Putin earlier this week, saying he did not propose extending a global oil output cut deal but said he recognized it was a possibility.
"Yesterday we had Russia and the Saudis talking about extending cooperation, and today we saw a little bit of backtracking with respect to additional cuts in production." said Houston-based consultant Andrew Lipow. "What the market gained yesterday is clearly being given back today."
Saudi Arabia's energy minister said on Thursday he was "flexible" about prolonging the production-curbing pact until the end of 2018.
However, concerns linger about growing U.S. crude exports, incentivised by a hefty WTI discount to Brent prices.
"We have a couple of bearish factors like a new record for U.S. crude exports, the reopening of Libya's biggest oilfield, a new year high in U.S. crude production and the recent strength of the U.S. dollar," said Frank Schallenberger, head of commodity research at LBBW in Stuttgart.
A stronger dollar also led to further losses in the oil market on Friday. The dollar hit a 10-week high after data showing the largest gain in U.S. wages since December 2016 bolstered bets on an interest rate hike by year-end.
"I expect Brent to drop below $55 a barrel and WTI below $50 in the next couple of days," Schallenberger said.
U.S. government data showed this week that crude exports had risen to a record of nearly 2 million barrels per day. Analysts told CNBC they expect the export levels to remain elevated in the coming weeks.
Futures held their losses after oilfield services firm Baker Hughes reported the number of oil rigs operating in U.S. fields fell by 2 in the latest week. The rig count stood at 748, compared with 428 at this time last year.
Investors were watching tropical storm Nate's impact on some oil production in the Gulf of Mexico ahead of its expected arrival in the area as a hurricane on Sunday.
"The biggest impact (from Nate) could be on gasoline prices, depending on how many refineries are forced to shut down. But I don't think we will see another bull run," said Frank Schallenberger, head of commodity research at LBBW in Stuttgart.
In the Gulf of Mexico, BP and Chevron were shutting production at all platforms, while Royal Dutch Shell and Anadarko Petroleum suspended some activity. Exxon Mobil, Statoil and other producers have withdrawn personnel.
— CNBC's Tom DiChristopher contributed to this report.