By Stephanie Yang 

Oil prices fell from a two-month high on Tuesday, as investors once again began to doubt OPEC's ability to curtail production and make a dent in the global supply glut.

Light, sweet crude for September delivery lost 56 cents, or 1.1%, to $49.57 a barrel, breaking a six-session winning streak that led prices above $50 a barrel for the first time since May 24. Brent, the global benchmark, fell 68 cents, or 1.3%, to $52.04 a barrel.

Signs of increasing production from the Organization of the Petroleum Exporting Countries have negated reassuring rhetoric by leading member Saudi Arabia, analysts said, which has announced plans to cap exports and enforce compliance in curtailing output.

The cartel, along with several other major oil producing nations, agreed to cut production late last year and extended the deal through March 2018. Still, prices have dropped in 2017 as market players have become more doubtful of OPEC's influence on global crude stocks. Meanwhile, U.S. shale activity has ramped up in response, helping offset the cuts from OPEC.

A Reuters survey this week showed OPEC production climbing in July to the highest level since December 2016, as Libya increased supply and some members slipped in compliance with the deal.

"The realization that OPEC oil production is at its highest level this year is undercutting some of the recent strength," said John Kilduff, founding partner at Again Capital. "I think there's a lot of skepticism."

Cargo tracking data has also indicated that OPEC exports increased in July despite the production deal, according to Robbie Fraser, commodity analyst at Schneider Electric.

"You've got the market really hesitant at this point to make any decisive move above $50 a barrel," said Mr. Fraser.

Traders will be closely watching for storage data from the U.S. Energy Information Administration, due at 10:30 a.m. ET on Wednesday. Prices have rallied in recent weeks on signs of declining supply in the U.S., as stockpiles have fallen six out of the past seven weeks.

Recent gains have also prompted some traders to take profits ahead of the EIA data, said Jim Ritterbusch, president of energy-advisory firm Ritterbusch & Associates.

The storage reports are "especially big right now," Mr. Fraser said. "If you want to point to a single justification of why prices have been able to claw their way back...those stock draws are really going to need to keep happening."

Write to Stephanie Yang at stephanie.yang@wsj.com

(END) Dow Jones Newswires

August 01, 2017 11:22 ET (15:22 GMT)