OPEC lowered its forecast for the global oil demand next year for a fourth straight month on Tuesday due to the slightly slower global economic growth.

The Organization of the Petroleum Exporting Countries (OPEC) said in its monthly report that the world oil demand growth is to decline to 1.29 million barrels a day in 2019 , about 70,000 barrels a day lower than its last month's projection.

The global economic growth forecast for 2019 was revised down slightly by 0.1 percentage point to 3.5 percent, on the back of a slowing dynamic amid rising trade tensions, monetary tightening, particularly in the U.S., and mounting challenges in emerging markets and developing economies, OPEC said.

Russia and Saudi Arabia have reportedly started discussions over the potential output cuts in 2019. Moreover, OPEC is reportedly considering cutting oil productions again next year following the output curbs issued in 2017.

OPEC and non-OPEC ministerial meeting in June decided to stick to 100 percent conformity of the oil production cap set in the meeting in 2016 in which the agreement to cut oil output by a total of 1.8 million barrels per day has been reached.