The Organization of Petroleum Exporting Countries (OPEC) on Thursday announced a slight rise to its global crude oil demand forecast for 2012 and 2013.

According to the latest monthly oil market report, OPEC predicted that global oil demand was expected to reach a daily average of 88.72 million barrels in 2012 and increase up to 89.52 million barrels a day in 2013.

This marks a rise of 40,000 and 20,000 barrels a day on previous forecasts in July.

The oil cartel believed that growth prospects remained although the global economy was facing difficulties. While the US economy showed slow recovery, Europe has been working to find solutions for solving the debt crisis. In addition, emerging markets are expected to keep a certain growth, it said.

However, a series of factors may have impacts on the global oil demand in the next period of time and world crude oil markets would face more uncertainty, it warned.

The monthly report also said that, against the slight increase of global oil demand, the demand of global oil market from the OPEC was expected to fall on the contrary due to the continuous rise of supply from non-OPEC oil-producing countries.

The world will need an average of 29.87 million barrels of crude oil a day from OPEC's 12 members this year and 29.51 million barrels a day in 2013, which was about 80,000 and 90,000 barrels a day less than in the previous report in July.

According to a latest report by Reuters, output from OPEC countries reached 31.75 million barrels a day in April, the highest level since September, 2008. Thereafter, it followed the downward trend in the next three month and decline to a daily average of 31.18 million barrels in July, which however still exceeded its limit on output of 30 million barrel a day.

Insiders said that if the cartel's oil output fall back to the limit, it will have a profound impact on global oil market and oil prices.