In its latest monthly report, the Organization of the Petroleum Exporting Countries said 2016 oil supply from outside the group will decline by 380,000 barrels per day to average 57.14 million per day.
The previous forecast from OPEC, which pumps around a third of the world's crude, was for a drop of 130,000 barrels per day for countries outside the 13-country group.
Oil prices have plunged by more than 60 per cent in the past 18 months due to a global supply glut and a weaker Chinese economy, with Brent crude falling under USD 40 this week for the first time since 2009.
Driven by cartel kingpin Saudi Arabia, this strategy is aimed at maintaining market share and squeezing out US producers of shale oil, whose output has boomed in recent years but which need a higher oil price to make money.
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The new December monthly report suggested however that its ploy may be taking longer than expected to bite, with the cartel obliged to increase its forecast for 2015 non-OPEC production.
The biggest expected drop in 2016 - of 110,000 barrels - will come from the United States, but the new report also showed that production from non-OPEC Russia hit post-Soviet records in October and November.
It added however that while the share of OPEC crude in global supply has fallen since 2008, in the first 11 months of 2015 it inched up 0.4 percentage points to 32.9 per cent.
In November, OPEC production increased by 230,000 barrels per day compared to the previous month to average 31.70 million, according to secondary sources, OPEC said.