Brent crude extended a two-month slide as OPEC's production was seen increasing and manufacturing gauges in Europe and China missed estimates. West Texas Intermediate fell in New York.

Futures slid as much as 0.4 percent in London, having retreated more than $9 in July and August. The Organization of Petroleum Exporting Countries boosted output by 891,000 barrels a day to 31 million in August, the highest level in a year, estimates compiled by Bloomberg show. Purchasing Manufacturing Indexes for Germany, Italy, the U.K. and China all came in below estimates for August. Floor trading in the U.S. is closed for the Labor Day holiday today.

"Those disappointing PMI numbers are helping push oil prices lower," Michael Hewson, a London-based analyst at CMC Markets Plc, said by e-mail. "Lower demand against expectations of higher production is helping cap the upside."

Brent for October settlement dropped as much as 37 cents to $102.82 a barrel on the London-based ICE Futures Europe exchange and was at $103.03 as of 3:23 p.m. local time. The volume of all futures traded was about 59 percent below the 100-day average for the time of day. Prices decreased 2.7 percent in August and 5.6 percent in July, the longest monthly falling streak since one that ended in May last year. Brent is down 7.1 percent this year.

WTI for October delivery slid as much as 44 cents to $95.52 a barrel in electronic trading on the New York Mercantile Exchange. Transactions will be booked tomorrow for settlement purposes. The European benchmark crude traded at a premium of $7.35 to WTI on ICE, compared with $7.23 on Aug. 29, which was the narrowest closing level since Aug. 14.