* OPEC oil output posts biggest drop since 2017 on Saudi move
* Oil volatile as markets roiled by Apple warning, U.S. data
* U.S. crude oil stocks fall 4.5 mln bbls -API (Updates with API data on U.S. crude stockpiles)
By Stephanie Kelly
NEW YORK, Jan 3 (Reuters) - Oil prices rose more than 1 percent on Thursday in volatile trade, drawing support from signs that Saudi Arabia is cutting crude output but pressured by concerns that slowing global economic growth could dent demand.
Brent crude LCOc1 futures gained $1.04 to settle at $55.95 a barrel, a 1.89 percent gain. U.S. West Texas Intermediate (WTI) crude CLc1 futures rose 55 cents to settle at $47.09 a barrel, a 1.18 percent gain.
Prices traded in a wide range, with Brent hitting a session high of $56.30 a barrel and a low of $53.93 a barrel. WTI posted a session high of $47.49 a barrel and a low of $45.35 a barrel.
Supporting futures were signs of reduced supply from members of the Organization of the Petroleum Exporting Countries. OPEC oil supply fell in December by the largest amount in almost two years, a Reuters survey found, as top exporter Saudi Arabia made an early start to a supply-limiting accord while Iran and Libya posted involuntary declines. led by Saudi Arabia, alongside allied producers led by Russia, agreed last year to rein in supplies starting from January after oil prices tumbled from above $86 on worries about surging output.
"The Saudis are still spearheading a significant production cut that became official this week. Thus far, strong adherence to adjusted quotas appears a high probability," Jim Ritterbusch, president of Ritterbusch and Associates, said in a note.
But oil price gains were capped by concerns about a faltering global economy.
Tech giant Apple Inc AAPL.O cut its sales forecast, citing a slowdown in China. .N The news rattled U.S. equity markets and weighed on oil prices, which at times track Wall Street.
Weaker-than-expected U.S. factory data also added to economic worries.
"Oil is flip-flopping on concerns of supply and demand," said Phil Flynn, an analyst at Price Futures Group in Chicago. "It's really a battle between the supply situation, which looks to be tightening, versus the possibility that demand will drop off."
U.S. oil and gas executives' outlook turned negative for the first time since the low point of the last oil bust, according to results of a survey released on Thursday by the Federal Reserve Bank of Dallas. have been concerned about rising supply from top producers, including the United States and Russia.
U.S. crude stocks fell last week, while gasoline and distillate inventories built, data from industry group the American Petroleum Institute showed on Thursday.
Crude inventories fell by 4.5 million barrels in the week ended Dec. 28 to 443.7 million, compared with analysts' expectations for a decrease of 3.1 million barrels.
Gasoline stocks rose by 8 million barrels, compared with analysts' expectations in a Reuters poll for a 2 million-barrel gain. Distillate fuels stockpiles rose by 4 million barrels, compared with expectations for a 1.6 million-barrel gain, the API data showed.
Official U.S. government data is due to be released on Friday.
Riyadh was expected to cut February prices for heavier crude grades sold to Asia due to weaker fuel oil margins while reducing prices for light grades to keep Saudi oil competitive against rising U.S. shale oil supplies, a Reuters survey showed on Thursday. GRAPHIC: Shanghai crude oil futures vs Brent & WTI crude
https://tmsnrt.rs/2AmwzBl GRAPHIC: Global crude oil supply & demand balance
https://tmsnrt.rs/2Sz1Isf
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