Brent crude hovered near $86 a barrel on Friday after dipping below that level in late morning trade on news of strong supply from Middle Eastern OPEC producers and as a confirmed case of Ebola in New York spooked global equities markets.
Iraq increased its oil supply in October, and Libya's production remained high, despite deep instability in both countries.
Brent crude for December fell $1.09 a barrel to $85.76 in early trading, near lows of the day. U.S. December crude fell $1.17 to $80.92 a barrel.
On Thursday, Brent crude prices rose sharply on news of lower supply from Saudi Arabia, although overall Saudi production increased month-on-month and some barrels went into storage.
Analysts said on Friday that the market had overreacted on the up side, given the increase in production.
"If Saudi Arabia is releasing less oil into the market despite rising production, this indicates weaker demand," said Carsten Fritsch, an analyst at Commerzbank, in a note.
"This can scarcely be interpreted as an argument for rising oil prices."