USA oil producers exported a record 1.3 million barrels of oil a day in May, according to the Houston Chronicle.
Brent crude fell almost 1 percent on concerns that the cutting of ties with Qatar could hamper a global deal to reduce oil production.
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The revision is another sign that USA drillers are taking full advantage of higher oil prices buoyed by OPEC 's deal with crude exporters to limit production in a bid to shrink a global oversupply.
USA stocks of crude oil and gasoline surprisingly rose last week as refinery runs declined and exports fell, the Energy Information Administration (EIA) said June 7. Forecasters had predicted a decline in inventories.
USA crude futures tumbled 5 percent, or $2.47 a barrel, to $45.72 a barrel, the lowest settlement for US crude since May 4.
On the New York Mercantile Exchange, crude futures for July delivery fell 0.55% to $47.14 a barrel, while on London's Intercontinental Exchange, Brent eased 0.44% at $49.23 a barrel.
The price moved more firmly above this key line of support, recovering some of its losses to trade back above $46 a barrel in mid-morning trade. Prices on Tuesday pared gains to close up 1.7 percent after the American Petroleum Institute was said to report stockpiles of the motor fuel increased by 4.08 million barrels last week.
But Qatar's isolation also caused trade disruptions that offered some short-term support for oil prices, analysts said.
"I think it's still going to be a bit of a debate on the true impact it can have on the oil market", said Olivier Jakob, strategist at Petromatrix, adding that a breakdown in relations between Qatar and Saudi Arabia could hamper an OPEC-led deal on production cuts.
Thursday's drop extended losses after a 5.1 percent plunge in the previous session, sparked by a bearish report on USA stockpiles of crude and gasoline stockpiles from the Energy Information Administration.
World fuel production and consumption is roughly in balance, at nearly 98 million bpd, although inventories remain somewhat bloated, according to the U.S. Energy Information Administration (EIA).
Traders will be paying attention to US inventories data over the next few days. The loonie was down 0.39 to 74.01 cents US.
U.S. Gasoline stocks also rose by 3.3 million barrels.
USA stock indexes were pulled down by Apple shares, which fell as the iPhone maker unveiled products and services at its annual developers conference.