World oil demand growth will slow in 2013 from the already weak 2012, OPEC said on Wednesday, citing Europe’s debt worries, a faltering U.S economic recovery and deceleration of growth in emerging markets. The Organization of the Petroleum Exporting Countries (OPEC), which produces a third of global oil, said daily average demand for its crude in 2013 would stay below its current production levels as additional barrels coming out of non-OPEC producers will be enough to compensate for modest demand growth. “Besides the euro zone crisis, geopolitical tensions in the Middle East, the contraction of manufacturing in the U.S. for the first time since 2010 and decelerating economic growth in emerging markets have been fuelling uncertainties regarding global economic growth,” OPEC said in a monthly report. OPEC left its 2012 world oil demand growth forecast unchanged at 0.9 million bpd and said growth in 2013 would amount to 0.82 million bpd. “The fact that the departure of Greece from the euro zone, with a severe impact on the euro zone economy, still cannot be ruled out remains a cause of concern,” it said. “Such an action would provoke a massive capital outflow from the country and result in a default of its fiscal obligations, with a destabilizing effect on the euro zone and beyond.” The group’s forecasts are close to those of the U.S. government, which on Tuesday cut its global oil demand growth estimate for 2013 by 360,000 bpd to 730,000 bpd. OPEC forecast non-OPEC supply to increase by 0.7 million bpd in 2012 and 0.9 million in 2013. “U.S. oil supply is expected to average 10.07 million bpd in 2013, an increase of 0.37 million bpd over 2012. This increase will be the highest among all non-OPEC countries and at the highest annual level since 1986,” OPEC said. OPEC also cited secondary sources as saying Iranian production was down to 2.963 million bpd in June, the lowest in more than 20 decades, while Saudi Arabia had ramped output back to above 10.1 million bpd.