"Net, we find that an agreement to cut production, while increasingly likely, remains premature given the high supply uncertainty in 2017," Goldman Sachs said in a note.

Such a deal would be "self-defeating if it were to target sustainably higher oil prices," Goldman said.

Oil has rallied more than 13% in less than two weeks since Opec proposed its first production curbs in eight years. Still, prices remain about half of mid-2014 highs above $100 a barrel.

On Tuesday, Brent crude settled down 73 cents, or 1.4%, at $52.41 a barrel, retreating from a one-year high of $53.73 hit on Monday.

US West Texas Intermediate (WTI) crude fell 56 cents, or 1%, to settle at $50.79.

Global oil industry officials in Istanbul for the World Energy Conference issued a raft of statements on Opec's production plan.

The energy ministers of Saudi Arabia and Russia intend to hold further consultations in Riyadh after the Istanbul meeting, the Saudi energy ministry said in a statement.

"I can say that many countries from outside Opec are willing to join... we are not talking about support, we are talking about contribution," Saudi Energy Minister Khalid al-Falih told Reuters on Tuesday in Istanbul.

But Igor Sechin, Russia's most influential oil executive and the head of Rosneft, told Reuters in an interview his company will not cut or freeze oil production as part of a possible agreement with Opec.

Russian Energy Minister Alexander Novak said the base-case scenario for Russia would be to leave current output unchanged.

Opec aims to cut production by 700,000 barrels per day to 32.5 million to 33 million bpd by its next policy meeting in Vienna on 30 November.

Opec has asked non-Opec producers besides Russia to contribute with cuts too, although the US, the world's top oil producer, will not be part of the plan.

Analysts worry that production of US shale oil, crimped this year by prices as low as nearly $26 a barrel, will begin to increase again if crude prices maintain their recent upward momentum.