The slide also comes during signs of a softer-than-expected impact from USA sanctions on Iran oil exports.
OPEC and non-OPEC energy ministers are due to meet in early December in Vienna to assess the global market.
"With Iranian waivers coming in higher than anyone expected, Saudi Arabia is acting responsibly by reducing its production that it had earlier brought online to offset possible Iranian losses", said Amrita Sen, chief oil analyst at Energy Aspects Ltd, a consultant in London.
In a final statement, they said they had "reviewed current oil supply and demand fundamentals and noted that 2019 prospects point to higher supply growth than global requirements".
The remarks came days after Brian Hook, the USA special representative for Iran, warned Iran's business partners to "rethink your decision" to buy Iranian oil in the wake of Washington's "toughest" sanctions against Tehran.
US West Texas Intermediate (WTI) crude oil futures were at $60.73 per barrel, up 54 cents, or 0.9 percent from their last settlement.
Major producers, including Russian Federation and Saudi Arabia, on Sunday warned that crude supply would outstrip demand next year at a joint OPEC non-OPEC ministerial monitoring committee meeting in Abu Dhabi. Saudi Arabia will cut production as well as exports, he said.
However, market participants say the global energy market could see another period of excessive supply of crude oil as soon as next year - with oil bulls looking at Bakken anxiously.
Ahead of the meeting, he acknowledged that so far there was no new deal to cut production among OPEC and non-OPEC producers, who struck an agreement in late 2016 to cut output by 1.8 million bpd to tackle an oversupply crisis.
It was "premature to talk about a specific action", he told reporters, asked about the possibility of an output cut to support sliding prices.
"This relief gives Iraq time to start taking steps towards energy independence", a video published on the US Embassy in Iraq's official Facebook page said.
"We want to enter 2019 with a minimum amount of stocks", Falih said.
Dudley said the waivers had been unexpected, so the market had been readjusting.
Producers implemented large cuts starting at the beginning of 2017 and managed to push up oil prices from below $30 a barrel to over $85 in October, strongly improving their revenues.
But the producer nations eased the output cuts in June after signs of a tight market and higher prices, allowing hundreds of thousands of extra barrels into the market.
Commerzbank, Germany's second-largest lender, said Friday that oil producers must act to prevent prices tumbling. "I think those reports are going to be even weaker because they will have to adjust for the increase in USA production", Jakob said.