On Thursday, OPEC tentatively agreed to an oil output cut. However, the energy organization could not decide on concrete reductions as it was awaiting Russia's definitions.
Iran, which came under U.S. sanctions in November, was also holding up a final deal. "Iran will insist on an exception until sanctions are removed," one of the OPEC sources said.
Additionally, Saudi Arabia has been facing pressure from U.S. President Donald Trump to refrain from cutting supplies. And with Trump aiming to continue to squeeze Tehran with sanctions, a global oil output reduction would benefit Iran through increased international prices.
Russian energy minister in discussions with Iran's oil minister Bijan Zanganeh here in Vienna, ahead of the Opec, non-Opec meeting later today. #Iran demands an exemption from any future cut. Saudis not open to the idea... yet. Novak in to try and bridge the gap. #oottpic.twitter.com/PlYwqn2zJg