By Sarah McFarlane, Alison Sider and Jenny W. Hsu 

Global crude futures wavered between slight gains and losses Friday, amid growing concerns that OPEC's pledge to reduce global inventories was encouraging the U.S. to boost production.

U.S. crude futures pared gains in earlier trading and were recently up 3 cents, or 0.06%, at $47.73 a barrel on the New York Mercantile Exchange. Brent, the global benchmark, was unchanged at $50.56 a barrel on ICE Futures Europe.

Prices have been largely treading water, hovering above a four-month low, ahead of a meeting of the committee charged with overseeing the implementation of the production-cut agreement struck late last year by the Organization of the Petroleum Exporting Countries and other nations.

The oil cartel and a group of non-OPEC heavyweights have agreed to cut output by 1.8 million barrels a day, but market participants are becoming increasingly anxious that the cuts haven't been enough to drain the global oil glut. Analysts and investors are watching for signs that the group will extend production cuts set to expire at the end of June.

"There's a lot of uncertainty about whether the cut is going to be in place long enough to alter the fundamental picture," said Gene McGillian, research manager for Tradition Energy. "People are waiting to see if anything comes out of the meeting -- if nothing comes out that can be viewed as substantial, we can expect further liquidation."

Crude prices have fallen by around nearly 12% since the beginning of March as analysts say rising production and growing stockpiles in the U.S. are foiling OPEC's efforts.

"Stocks do seem to be growing at least in the U.S. and a couple of the other OECD regions, rig counts are increasing, U.S. production is increasing, investors seem to have lost some confidence," said Tom Pugh, a commodities analyst at Capital Economics.

U.S. shale-oil production has climbed nearly 5% since the first week of December, data from the U.S. Energy Information Administration showed, and total output has stayed above the 9-million-barrel-a-day threshold for the past four weeks. Meanwhile U.S. crude stocks rose more sharply than expected to a fresh high in the week ended March 17.

"[The] U.S. is acting as a bellwether for the global stock overhang. With little sign of an imminent rebalancing in U.S. crude inventories, the near-term risks for oil prices remain skewed to the downside," said brokerage PVM.

That will put more pressure on the monitoring committee overseeing compliance with the production-cut agreement as it meets this weekend.

"I think that they know they are going to be under pressure, prices aren't much higher than when the first deal was struck, and stocks are not much lower, so for every reason that you had to do the original deal, all those reasons are still valid," said Mr. Pugh.

"The sticking point is going to be Iran, Saudi will want them to join in any cuts, I think that will probably result in a compromise where Iran agrees to freeze its production at current levels."

The original deal among OPEC members agreed on Nov. 30 allowed Iran a limited output increase.

Saudi Arabia, which is shouldering the bulk of the cuts, will likely lobby to extend the plan, especially after ratings company Fitch cut the kingdom's credit rating to A+ from AA- and lowered the outlook to negative from stable, citing a worsening government deficit caused by declining oil prices, said Stuart Ive, a client manager at OM Financial.

"OPEC is feeling the pressure. It may pay to go into the weekend long with a tight stop or look at optionality to reflect a spike come Monday, " he said.

Market players will also be watching the weekly U.S. rig count before placing bets. In the week ended March 17, U.S. drillers activated 14 more rigs, the ninth straight week of additions.

Gasoline futures were recently down 0.47 cent, or 0.3%, at $1.5849 a gallon. Diesel futures were down 0.15 cent, or 0.1%, at $1.4886 a gallon.

Write to Sarah McFarlane at sarah.mcfarlane@wsj.com, Alison Sider at alison.sider@wsj.com and Jenny W. Hsu at jenny.hsu@wsj.com

(END) Dow Jones Newswires

March 24, 2017 11:50 ET (15:50 GMT)

Copyright (c) 2017 Dow Jones & Company, Inc.