Oil prices fell on Thursday on expectations that OPEC members will step up production in the face of worries over supply from both Venezuela and Iran.
A surprise build up in crude oil inventories in the United States also weighed on prices, driving the spread between Brent crude and U.S. West Texas Intermediate (WTI) close to its widest in three years.
International benchmark Brent futures were down 37 cents, or 0.46 percent, at $79.43 per barrel at 0610 GMT.
WTI crude futures were down 27 cents, or 0.38 percent, at $71.57 a barrel.
The Organization of Petroleum Exporting Countries (OPEC) may decide to increase oil output to make up reduced supply from Iran and Venezuela in response to concerns from Washington over a rally in oil prices, OPEC and oil industry sources told Reuters.
Supply concerns in Iran and Venezuela following new U.S. sanctions had pushed both Brent and WTI to multi-year highs, with Brent breaking through an $80 threshold last week for the first time since November 2014.
"The chat is still that OPEC will do something at its June meeting in reaction to the looming prospect of a fall in crude production and exports from both Iran and Venezuela as the year progresses," said Greg McKenna, chief market strategist at CFD and FX provider AxiTrader.