US crude futures hit their lowest level since June 22, 2017, while Brent crude hit its lowest level since August 17, 2017.
Markets across all asset levels were under pressure as growing concerns over the US government’s shutdown. Investors turned to safe havens like gold and US debt instruments.
US crude futures were settled at $ 42.53 a barrel, down $ 3.06, or 6.7 percent, at the session.
Brent crude fell $ 3.35 a barrel, or 6.2 percent, to settle at $ 50.47 a barrel.
Brent fell 11 percent last week to its lowest level since September 2017, while US futures contracts hit their lowest level since July 2017, bringing the contract down to 35 percent in the quarter.
The Organization of the Petroleum Exporting Countries (OPEC) and Russia agreed earlier this month to cut production by 1.2 million bpd starting in January to curb supply.
UAE Energy Minister Suhail al-Mazroui said on Sunday that OPEC and its allies would hold an extraordinary meeting if the cuts did not stop to balance the market.