World oil prices were narrowly mixed on Thursday with OPEC expected to maintain its output ceiling at a meeting in Vienna.
New York's main contract, light sweet crude for delivery in July, gained 18 cents to $82.80 a barrel.
Brent North Sea crude for July fell 17 cents to $96.96 a barrel in London midday trade.
"The market was holding its breath ahead of today's OPEC regular policy meeting in Vienna, at which we expect no changes to the exporting group's current production target of 30" million barrels per day (mbpd), said Andrey Kryuchenkov, a commodities analyst at Russian financial group VTB Capital.
OPEC's dozen nation members are in fact collectively pumping out more than the ceiling, with estimates ranging from between one and three mbpd extra, helping to push down oil prices.
Brent crude prices have slumped by about a quarter since March -- mainly on expectations of weaker demand caused by the eurozone debt crisis and amid a slowing Chinese economy.
The price of Brent crude oil -- the European benchmark -- has tumbled from $128 a barrel in early March.
The Organization of Petroleum Exporting Countries (OPEC) pumps out about one third of the world's oil.