Oil retreated for the fourth consecutive session on Wednesday in anticipation of a rise in U.S. crude stocks and on the possibility of increased supplies from OPEC.

U.S. light crude for December delivery fell 27 cents to $85.00 a barrel at 7:06 a.m.

London Brent crude eased 6 cents to $82.79.

Oil has fallen around $5 a barrel from a record high of $90.07 set on Friday, but has gained about 40 percent this year on fears of a supply shortfall in the northern hemisphere's winter season and on tensions in the Middle East.

The debate remains very much alive as to whether the oil market remains seriously under-supplied going into winter, investment bank Citi said in a research note.

A move north of $95 or a move south of $80 both appear possible right now.

The U.S. Energy Information Administration will give its weekly snapshot of oil and fuel supplies in the world's biggest oil consumer later on Wednesday.

A Reuters poll predicted that U.S. crude and gasoline stocks each rose by 800,000 barrels last week.

China, the world's second largest oil consumer, has complained that oil prices are too high as the country's energy officials meet with OPEC in Beijing.

The Organization of the Petroleum Exporting Countries has already agreed to increase oil output from November but Petrologistics, a consultancy which tracks tanker movements, said on Tuesday OPEC was already raising oil supply in October in response to record prices.

OPEC sources are also talking of a possible further increase.

My personal view is I think we need to increase another 500,000 barrels per day in November, said one of the more senior delegates in OPEC.

Tensions between Iraq and Turkey over Kurdish rebels operating from the north of Iraq are still simmering.

Turkish warplanes and troops have attacked Kurdish rebels inside Iraq and forces have been built up on the border, but Ankara has held back from any major strike for now.

Mexico closed its main oil exporting ports due to bad weather on Tuesday, shutting off the bulk of the country's crude shipments to the United States.

(Reporting by Randy Fabi in London and Annika Breidthardt in Singapore)