Oil prices turned negative amid a sell-off in the U.S stock market on Monday, with U.S. crude posting an 11th straight day of losses, its longest longest losing streak on record.

Crude futures looked set to break the streak earlier on Monday after Saudi energy minister Khalid al Falih said OPEC and its allies may need to cut crude production by about 1 million barrels per day to prevent the market from swinging into oversupply. On Sunday, Falih said the kingdom's shipments would fall by 500,000 bpd in December.

But the recent strong correlation between stocks and crude futures reasserted itself on Monday as the Dow Jones Industrial Average fell 600 points.

"The stock market was pulling at the oil complex all day. We should have gotten more of rally at that Saudi commentary over the weekend," said John Kilduff, founding partner at energy hedge fund Again Capital.

U.S. West Texas Intermediate crude settled 26 cents lower at $59.93 on Monday, falling deeper into bear market territory. The contract has never fallen for 11 straight days since it began trading in New York more than three decades ago.

The losses continued after the settlement, with WTI falling more than 2 percent and dipping below $59 a barrel for the first time since February.

Brent crude, the international benchmark for oil prices, settled 6 cents lower at $70.12 on Monday. Brent briefly dipped below $69 to its lowest level since April in post-settlement trade.

Crude futures have pulled back sharply during the last five weeks, as oil got swept up in October's market sell-off that saw investors shed risk assets. Rising oil supplies from the United States, OPEC and Russia and forecasts for weaker-than-expected demand growth have kept pressure on the market.

"It does look like demand is starting to come off a bit," BP CEO Bob Dudley told CNBC at the ADIPEC oil and gas conference in Abu Dhabi on Monday.

The world's appetite for oil now looks set to grow by about 1.3 million bpd, compared with BP's earlier expectations for 1.4 million to 1.5 million bpd of growth, Dudley said.