* Oil volatile as markets roiled by Apple warning, U.S. data
* Saudi Arabia may cut Feb heavy crude prices to Asia
* OPEC oil output posts biggest drop since 2017 on Saudi move
* Coming up: API data on U.S. crude inventories (New throughout, updates prices, market activity and comments; new byline, changes dateline, previous LONDON)
By Stephanie Kelly
NEW YORK, Jan 3 (Reuters) - Oil prices edged lower in choppy trade on Thursday, pressured by concerns about slowing global economic growth that could dent demand for crude but drawing support from signs of output cuts by Saudi Arabia.
Brent crude futures fell 27 cents to $54.64 a barrel by 10:46 a.m. EST (1546 GMT). U.S. West Texas Intermediate (WTI) crude futures fell 60 cents to $45.94 a barrel, a 1.3 percent loss.
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.
Crude futures mirrored volatility in other markets after tech giant Apple cut its sales forecast, citing a slowdown in China. The news rattled U.S. equity markets and weighed on oil prices, which have recently moved in tandem with Wall Street.
Weaker-than-expected U.S. factory data added to worries about a slowing global economy.
"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."
Supporting futures were signs of reduced supply from OPEC members. 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.
"The feeling is that OPEC is delivering on cuts," SEB head of commodities Bjarne Schieldrop said.
The Organization of the Petroleum Exporting Countries 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.
Investors have been concerned about rising supply from top producers, including the United States and Russia.
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.
Supply from Iraq, the second biggest producer in OPEC, has also climbed, with December exports at 3.73 million bpd versus 3.37 million bpd in November.
Additional reporting by Noah Browning in London Editing by Dale Hudson, Edmund Blair and David Gregorio