The Iranian OPEC governor had on Thursday taunted Trump for his tweets urging OPEC to reduce prices, saying the U.S. president's tweets have backfired, having driven the prices up by at least $10 per barrel.
US crude futures slipped on Thursday after data showed an unexpected 1.3 million-barrel build in crude inventories.
Brent crude futures LCOc1 were at $77.78 per barrel at 0137 GMT, down 46 cents, or 0.6 percent, from their last close.
Trump again accused the Organization of the Petroleum Exporting Countries of driving fuel prices higher on Wednesday, and urged United States allies such as Saudi Arabia to pump more oil. This must be a two way street.
The comments this morning follow on from yesterday's news that Saudi Arabia raised oil output by about 500,000 barrels per day in June.
OPEC together with a group of non-OPEC producers led by Russian Federation started to withhold output in 2017 to prop up prices.More news: 'Proud' Sweden march through to the World Cup quarter-finals
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OPEC and Russian Federation announced in June they were willing to raise output to address concerns of emerging supply shortages due to unplanned disruptions from Venezuela to Libya, and likely also to replace a potential fall in Iranian supplies due to U.S. sanctions.
Oil Industry experts believe Opec's biggest member can raise output by about 1 million bpd to 11 million bpd and even that would be a tall order in the short term.
US tariffs on $34 billion in Chinese imports took effect as a deadline passed on Friday and Beijing has vowed to respond immediately in kind, setting the two world's biggest economies on a path towards a full-blown trade conflict.
Goldman Sachs said the market will stay in deficit in the second half of the year as actual and potential supply losses from Iran, Venezuela, Libya and Canada far exceed the proposed boost from Opec and its partners.
Saudi Arabia on Thursday said that it would be reducing prices of its Arab Light grade crude exports.
The US has asked countries to cut all oil imports from Iran by the start of November or else face powerful sanctions, a senior official of the State Department stated.