Oil prices fell on concerns over a slowdown in the Chinese economy and concerns over the global oil oversupply. The oil driller Baker Hughes reported that the number of active U.S. rigs rose by 1 rigs to 675 last week. It was the sixth consecutive increase. Combined oil and gas rigs fell by 8 to 877.
The Chinese stock market declined on Monday. The Financial Times reported that the Chinese government ended its large-scale share purchase programme.
OPEC expressed concerns over the decline in oil prices in its bulletin on Monday.
"As the Organization has stressed on numerous occasions, it stands ready to talk to all other producers. But this has to be on a level playing field. OPEC will protect its own interests," OPEC said.
WTI crude oil for October delivery decreased to $43.60 a barrel on the New York Mercantile Exchange.
Brent crude oil for October fell to $48.62 a barrel on ICE Futures Europe.