"Prices are finding support from the prospect of OPEC oil production remaining restricted beyond mid-year", said Carsten Fritsch, an analyst at Commerzbank.
OPEC is set to meet on June 25, followed by talks with its allies led by Russian Federation on June 26.
U.S. President Donald Trump said he was ready to impose another round of punitive tariffs on Chinese imports if he does not reach a trade deal with China's president at a Group of 20 summit later this month.
Front-month Brent crude futures, the global benchmark for oil prices, were at $63.71 which represents 42 cents, or 0.7 per cent, above Friday's close.
The charter has been delayed over disagreements on how structured or loose to make the OPEC/non-OPEC coalition."The current status of the global oil markets, which are volatile once again, makes the Saudi-Russian cooperation all the more important", Falih said in a speech at the Moscow summit. "We've agreed that we need to run a deeper analysis and to see how events unfold in June", before making a decision on the future of output cuts with OPEC+.
Asked to comment on Siluanov's words, Novak told reporters in Russian Federation today that such a scenario of a sharp drop in prices is not to be ruled out.
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He died after having his face smeared with the outlawed VX nerve agent as he waited at Kuala Lumpur International Airport. Fifield similarly cites "someone with knowledge of the intelligence who spoke on condition of anonymity".
Brent crude futures, the worldwide benchmark for oil prices, were down 87 cents, or 1.4 percent, at $61.42 a barrel by 0231 GMT.
Saudi Energy Minister Khalid Al-Falih has talked up the prospects for an agreement to extend, and said Monday that producer countries would strive to prevent a price slump below $40.
Several OPEC sources said the most likely scenario now was keeping the production cut steady in the second half of 2019.
Oil prices fell more than 1 percent on Wednesday, weighed down by a weaker oil demand outlook and a rise in United States crude inventories despite growing expectations of ongoing OPEC-led supply cuts.
Stock markets rose on Monday after a deal between the United States and Mexico to combat illegal migration from Central America late last week removed the threat of US tariffs on goods imported from Mexico. "Saudi Arabia also may be interested in taking a stake in Russian petrochemical producer Sibur Holding", he said.
The minister also said Saudi Aramco had extended its offer to join Russian gas producer Novatek's Arctic LNG 2 project and that he hoped Novatek would agree to it, TASS news agency reported.