OPEC's Secretary General Mohammad Barkindo had said he expects non-OPEC countries would agree to output cuts of 600,000 barrels a day.
"For OPEC and non-OPEC we expect 600,000 or even more," he told reporters on Saturday, TASS reports.
The official also said he expected the cartel and non-cartel countries would sign a "historic" declaration after the main meeting.
The secretary general said he expected eleven non-residents, besides Russia, would join the agreement.
