Brent for August settlement traded at US$45.91 a barrel, down 11 USA cents, on the London-based ICE Futures Europe exchange.
The U.S. benchmark dropped 98 cents, or 2.3 percent, to $42.53 a barrel in NY.
Analysts said rising US crude production has fed the global glut.
After bottoming in July, the oil production in the United States has recovered by 0.9 million barrels per day that undermine the OPEC and participating non-OPEC countries' efforts to reduce production supplies by 1.76 million barrels per day.
USA oil production rose by 20,000 barrels a day last week to 9.35 million, the EIA reported Wednesday.
Both benchmarks are down around 15 percent since late May, when OPEC, Russia and other producers extended by nine months the cut in output by 1.8 million barrels per day (bpd). USA oil production increased to the highest since August 2015, according to a report from the Energy Information Administration.
Last week, OPEC countries and a group of other oil-producing nations, led by Russian Federation, agreed to extend the cuts by nine months until next March.
A bigger-than-expected cut in U.S. crude stockpiles reported overnight is barely shifting the dial.
He went on to say that OPEC should "wait a while and see how the market will form". The US Energy Information Administration predicts global oil stocks will draw down in the third quarter of 2017 as a result of Opec's output cuts.
At the same time, an increase in the number of drilled-but-uncompleted wells could drive oil prices down further, analysts said.
Despite the fact that OPEC countries and other oil-producing countries have been cutting production since January, investors still believe that their agreement is ineffective.
Ahead of weekly USA inventory reports, US crude oil stocks were forecast to have fallen for the second straight week, while gasoline supplies were seen unchanged after last week's data showed an unexpected build that weighed down the market.