Oil ends down after swinging on OPEC speculation; Brent below $80/bbl

By Barani Krishnan

NEW YORK (Reuters) - Crude prices ended lower, with Brent below $80 a barrel, after a volatile session on Monday as Russia's offer to add to OPEC output cuts led some to bet the group will agree on a higher production cut than thought when it meets this week.

Russia, which needs higher oil prices to support its economy, tried to sway OPEC to slash production, suggesting Moscow could cut its own crude output by about 300,000 barrels per day (bpd).

Oil ministers from the Organization of the Petroleum Exporting Countries meet on Thursday in Vienna and some are imploring the group to cut 1 million bpd or more to support prices that have fallen about 30 percent since June on fears of oversupply.

"Compared to a week ago, there's more speculation now of an higher-than-expected OPEC production cut," said Phil Flynn, analyst at Price Futures Group in Chicago.

"If you were oversupplied by 2 million bpd and you were planning to going to cut just 1 million, it would not have changed the situation much. But if the Russians came on board with another 300,000 bpd, then, yes, it would help."

Not all traders were convinced though that the Russian gesture would persuade OPEC.

Oil prices which initially rose midmorning in New York after a weak start, fell again by the close.

"I think it's going to be like this till we get the news on Thursday on where OPEC stands," said John Kilduff, partner at New York energy hedge fund Again Capital.

Benchmark Brent crude oil's front-month contract finished down 68 cents at $79.68 a barrel. It traded between a session low of $79.50 and a high of $80.85.

U.S. crude's front-month ended 73 cents lower, moving between $75.48 and $77.02.

A extension to Iran's nuclear talks, which maintains Western sanctions preventing Tehran from freely exporting its oil, limited some of the market's downside, traders said.

Fund managers say oil prices could plunge to $60 a barrel if OPEC fails to make significant cuts.

(Additional reporting by Jack Stubbs and Ahmed Aboulenein in London and Henning Gloystein in Singapore; Editing by Christopher Johnson, David Gregorio and Marguerita Choy)