Russia is meeting its obligations under the OPEC/non-OPEC crude production agreement, and participants remain committed to the arrangement, despite ongoing uncertainty over world energy market developments.

OPEC is due to meet in June, where the Iran question will no doubt be raised. But oil and gas leaders are taking a cautious approach, with Kuwait's oil minister Khaled Al Fadhel noting that a decision would be taken only after a review of oil prices.

Asked whether Iran’s oil could be removed from the market, Mr. Barkindo said: “No repetition is needed. Eliminating Iran from the oil market is impossible.”

Oil prices fell on Monday, extending a slump from Friday that ended weeks of rallying, after President Donald Trump demanded that producer club OPEC raise output to soften the impact of U.S. sanctions against Iran.

Putin said Ukraine was overpaying for gas which it could get much cheaper if it signed a transit deal with Russia.

"Not extending the oil waivers of some countries is another side of the US measures against Iran. But if Iran's oil is fully sanctioned, oil price will go higher than $100 per barrel,"

Oil prices dipped on Friday on expectations that producer club OPEC will soon raise output to make up for a decline in exports from Iran following a hardening of sanctions on Tehran by the United States.

Crude oil prices are expected to average $66 a barrel in 2019 and $65 a barrel in 2020,

Crude oil prices for spot delivery rose to 2019 highs earlier in the week after the United States said on Monday it would end all exemptions for sanctions against Iran, demanding countries halt oil imports from Tehran from May or face punitive action from Washington.

The International Energy Agency is monitoring developments in global oil markets, and notes that markets are now adequately supplied, and that global spare production capacity remains at comfortable levels.