LONDON - OPEC cut its forecast for world economic growth this year on Tuesday, citing increased uncertainty following Britain's vote to leave the EU and said the pace of oil demand growth would slow slightly next year in its first 2017 forecast.

However, the Organization of the Petroleum Exporting Countries in a monthly report was upbeat on the oil market outlook for 2017, saying global demand for its crude would be higher than its current production and excess oil inventories would be whittled down.

"After the U.K.'s referendum to leave the EU, economic uncertainty has increased," OPEC said in the report. "Potential negative effects have led to a downward revision of global economic growth in 2016 to 3.0 per cent from 3.1 per cent."

World oil demand will rise by 1.15 million barrels per day (bpd) in 2017, OPEC said, its first forecast for next year in the monthly report. That marks a slight slowdown from growth of 1.19 million bpd in 2016.