The price for a barrel of Brent crude oil for October delivery lost 5.16% to $83.39 a barrel, while US crude, or WTI, futures for September delivery declined nearly 6% to $79.66 per barrel.
Crude declined after US President Donald Trump said fresh talks with Iran would begin later in the day, easing concerns over potential supply disruptions. Additional downward pressure came after Saudi Arabia, Russia and five other key members of OPEC+ agreed in an online meeting on Sunday to boost oil production by 188,000 barrels a day from September, against a backdrop of disruption caused by the Middle East conflict.
"The seven participating countries decided to implement a production adjustment of 188 thousand barrels per day," they said in a joint statement.
The increase, decided by the key countries in the enlarged Organisation of the Petroleum Exporting Countries, was widely expected by analysts.
"OPEC+ has finished unwinding its voluntary cuts. The next challenge is managing the surplus that could emerge as export flows normalise," Jorge Leon, analyst at Rystad Energy, said.
