An oil platform of Petrobras floats in the Atlantic Ocean, near the Guanabara Bay, in Rio de Janeiro.
Oil prices fell on Monday, prolonging a decline on Friday that ended weeks of recovery after President Donald Trump demanded that OPEC's producer club increase production to ease the impact of US sanctions on Iran.
Brent crude futures were at $ 71.59 a barrel at 0840 GMT, down 56 cents, or 0.78 percent, from the last close.
US West Texas Intermediate (WTI) futures were at $ 62.93 a barrel, down 37 cents, or 0.58 percent, from the previous deal.
Both benchmarks fell about 3% in the previous session. Trump said on Friday that he told the Organization of Petroleum Exporting Countries (OPEC) to cut oil prices.
"Gas prices are falling, I called OPEC, I said that you have to take them down, you have to take them down," Trump told reporters.
"I have spoken to Saudi Arabia and others about the increased flow of oil," he said on Twitter.
Trump's comments triggered a selloff, putting at least one temporary ceiling on a 40 percent rise in oil prices since the beginning of the year. The demonstration strengthened in April after Trump tightened sanctions on Iran by ending all the exemptions that large buyers, especially in Asia, had previously had.
Traders said the market is shifting its focus to OPEC-led supply cuts, led by the world's biggest exporter, Saudi Arabia.
"We are of the opinion that Saudi Arabia is going to increase production as early as May, something they would probably do anyway until summer," ING Bank said. "The Kingdom could increase production by 500 million barrels per day (bpd) and still be in compliance with the OPEC + agreement for the month of May."
The cuts were backed by some non-OPEC producers, especially Russia, but analysts said that such cooperation could not last beyond a meeting between OPEC and its other allies, a group known as OPEC +, scheduled for June.
Russia said it will be able to meet China's oil demand needs while Beijing tries to replace the imports it normally receives from Iran.
"Russia seems to have every reason to resume production levels and the baseline scenario should begin to be (that) we will not see OPEC + agree to extend production cuts, with adjustments to cover Iran's shortfall," said Edward Moya, senior analyst at OANDA futures brokerage.