Oil prices continued to decline for the third session, affected by a larger-than-expected increase in crude and gasoline inventories in the United States and decreased concerns about supplies. By 0138 GMT, Brent crude futures fell 41 cents, equivalent to 0.48 percent, to $85.41 per barrel. While US West Texas Intermediate crude fell 49 cents, or 0.59 percent, to $83 per barrel.
Both benchmarks gave up most of their gains at the beginning of the week.
US crude oil inventories increased by about 12.9 million barrels, according to market sources, citing figures from the American Petroleum Institute, on Wednesday.
This is much higher than the increase of 500,000 barrels that analysts expected in a Reuters poll.
The data showed that gasoline stocks also rose by 3.6 million barrels, which is completely contrary to the decline of 800,000 barrels that analysts expected, as fears of a slowdown in demand for fuel in the United States continue.
Markets are awaiting more data on inventories from the US Energy Information Administration, scheduled to be released later today at 1430 GMT.
