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Published: Sept 21, 2016 5:56 a.m. ET

Energy Information Administration will be released later today.

Bloomberg News/Landov
Pumping jack near Almetyevsk, Russia, in July 2015.

Oil prices gained Wednesday after preliminary data showed a fall in U.S. crude inventories and there was speculation about an output deal between major producers as investors waited for the conclusion of the Federal Reserve’s policy meeting.

Brent crude LCOX6, +1.46%  , the global oil benchmark, rose 1.6% to $46.62 a barrel on London’s ICE Futures exchange. On the New York Mercantile Exchange, West Texas Intermediate futures CLX6, +1.88% were trading up 2% at $44.91 a barrel.

Prices rose after the American Petroleum Institute, an industry group, said late Tuesday that U.S. crude stockpiles fell by 7.5-million barrels last week. The U.S. Energy Information Administration will release its official inventory data later on Wednesday, and analysts surveyed by The Wall Street Journal expect a 3.3-million-barrel increase in stocks.

Meanwhile, Russia’s permanent representative to the Organization of the Petroleum Exporting Countries, Vladimir Voronkov said Russia would back a deal to stabilize oil markets for a year, according to Moscow-based news agency Interfax.

However, many traders and analysts say longstanding political tensions among the OPEC members could hinder progress. OPEC members have repeatedly tried and failed to agree on a deal to freeze their output in order to boost prices during oil’s more than two-year-old slump.

OPEC is holding a meeting next Wednesday in Algeria, but some officials have said no decisions would be taken as the meeting is an informal one.

“We just cannot see how OPEC and Russia would be able to reach a freeze accord and even less so a production cut accord,” said Bjarne Schieldrop, chief commodities analyst at SEB Markets.

Even if a production freeze is agreed, market fundamentals will see little changes given that most members are pumping at or near maximum capacity, according to BMI Research. OPEC’s production grew by 500,000 barrels a day in July and August owing to record Saudi Arabian production and more coming from Iraq, Iran and Kuwait.

Investors are also focused on the Federal Reserve’s September monetary policy meeting, concluding later Wednesday. While few expect the bank to raise rates, any hints at a rise in December could affect the U.S. dollar. With commodities such as oil being priced in the greenback, big moves in the dollar usually have an outsize impact on prices.

Nymex reformulated gasoline blendstock RBZ6, +1.80% — the benchmark gasoline contract — rose 2.2% to $1.39 a gallon.