The Organization of Petroleum Exporting Countries (OPEC) oil supply recorded a three-year high in July, reaching 31.51 million barrels a day, according to its report released on Tuesday.
OPEC, accounting for over 30 percent of global oil supplies in July, increased its output by 100,700 barrels a day to 31.5 million barrels a day.
The cartel group said the increase mostly comes from Iraq, Angola, Saudi Arabia and Iran, while production in Libya showed the largest drop, according to "secondary source".
Iran reached a historic agreement on its nuclear issue with world major powers in July, raising the expectation of its oil production revival in the coming moths.
Tehran increased its output by 32,300 barrels a day in July to 2.86 million a day, also the highest since June 2012, according to the report.
In June 2012, western states imposed tough sanctions against Iran, including oil embargo.
The cartel adjusted its forecast for global oil demand in 2016 by about 100,000 barrels a day.
