"Increased Saudi crude availability that is being enhanced by reduced OSPs (official selling prices) into Europe and other regions is providing a strong counter against curtailed Libyan export activities", Ritterbusch wrote.
Although Saudi Arabia and Russian Federation have said they would raise output to make up for disruptions, FGE said "there simply is not enough capacity to make up for Iran's crude losses, plus Venezuela and Libya", and warned of the possibility of oil prices rising to $100 per barrel.
Brent crude futures fell 25 cents, or 0.3 percent, to $77.14 per barrel by 0317 GMT from their last close. The supply increase reversed some of the cuts that OPEC and other major producers put in place in early 2017 to end several years of supply glut. Rising gasoline prices could create a political headache for Trump before November mid-term congressional elections by offsetting Republican claims that his tax cuts and rollbacks of federal regulations have helped boost the US economy. The global benchmark traded at a US$6.11 premium to WTI for the same month.
"The more that Saudi Arabia adds to the market, the less of a supply cushion we have - that's a bullish twist to a bearish development", said Yawger at Mizuho.
"You are hammering on good guys in OPEC".
"Countries around the world-including key American allies and partners-already find themselves in the crosshairs, since the US measures penalize countries and companies that do business with Iran", wrote Suzanne Maloney, deputy director of foreign policy and senior fellow at the Center for Middle East Policy, Energy Security and Climate Initiative at the Brookings Institution.
The average price of gasoline in the USA has risen above $3 per gallon.
An Iranian oil official said the USA president should stop tweeting about oil because Mr. Trump is making the situation worse, according to Bloomberg News.
In a tweet on Saturday, Trump said Saudi Arabia had agreed to increase oil output by up to 2 million barrels, an assertion the White House rowed back on in a subsequent statement.
Energy consultancy FGE this week issued a stark warning of looming supply shortages due to U.S. sanctions against Iran and also because of disruptions elsewhere.
Traders said the decline in fuel inventories was largely down to the outage at Syncrude Canada's 360,000 barrels per day (bpd) oil sands facility near Fort McMurray, Alberta, which is expected to last through July.