Russia says it may gradually raise output
Brent crude futures were at $78.78 per barrel at 0024 GMT, down 1 cent from their last close, but more than 2 percent below the $80.50 November 2014 high they reached on May 17. Brent broke through $80 for the first time in a few years earlier in May.
U.S. West Texas Intermediate (WTI) crude futures were at $70.69 a barrel, down 2 cents from their last settlement.
"Oil prices are now starting to drift a little," said Greg McKenna, chief market strategist at futures brokerage AxiTrader, adding that this was due to OPEC's and Russia's "moves toward an increase in production at the June meeting".
But Russia, in particular, has been floating a potential end to the production cuts, with energy minister Alexander Novak saying on Thursday that restrictions on oil production could be eased "softly" if OPEC and non-OPEC countries see the oil market balancing in June.
"The Russians have always struck me as production cut tourists keen to get off the boat and crank up production as soon as inventories were stabilized and prices once again elevated ... That possibility is top of the mind for traders and as a result oil prices are slipping," McKenna said.