The barrel of West Texas Intermediate marched higher toward the $70 mark during the first half of the day but reversed its course in the NA session as the latest trade headlines raised concerns over the potential negative impact of the U.S. - China trade conflict on the world oil demand. Problems with supply are already being felt with most nations complying ahead of time with USA demands to end all exports of oil from Iran.
The producer group said in June that it would agree to some supply increases starting in July, though the specific targets were not announced at the time.
US President Donald Trump called for OPEC members, primarily US ally Saudi Arabia, to raise their production, and warned importers to stop buying oil from Iran or face American sanctions.
Brent crude futures were up $1.03 a barrel to $79.09 a barrel at 0923 GMT, after hitting $79.32.
"The market's expectation of shortages has cooled after data from last week showed increases in supplies, while investors have lowered the outlook for oil demand", said Wang Xiao, head of crude research with Guotai Junan Futures.
Crude has mostly stayed below $70 a barrel since mid-July as a trade dispute between the USA and China threaten global economic growth.
Iran told on Sunday no member country should be allowed to take over another member's share of oil exports, expressing Tehran's concern about Saudi Arabia's offer to pump more oil in the face of USA sanctions on Iranian oil sales.More news: Klopp: Salah is in form
United States crude inventories likely fell 2.5 million barrels last week, according to a Bloomberg survey of analysts.
"Mr. Trump's attempt to prevent Iran from appearing on the global crude oil markets has allowed Russian Federation and Saudi Arabia, which would not favour low prices, to pursue hostage-taking policies in the market", Iranian OPEC governor Hossein Kazempour Ardebili said on Saturday.
Elsewhere, Russia's energy minister, Alexander Novak, said on Monday that the country was ready to discuss cooperation with the United States to balance the oil market.
Brent may fall more than $1 to $76.37 a barrel, while WTI crude prices may revisit their September 14 low of $67.94, he wrote.
Iran is the third-largest producer among the members of the Organization of the Petroleum Exporting Countries (OPEC).