Opec's monthly oil market report suggested total output among member countries rose 100,700 barrels per day to 31.5m.
The increase was driven partly by Iran, which increased oil output to 2.86m barrels per day, its highest level since June 2012. That figure was up from 2.83m in June. International sanctions against Iran started in July 2012.
But Saudi Arabia, Opec’s largest oil producer, said it had reduced production to 10.36m barrels per day in July, down from 10.56m in June.
Global demand for Opec crude oil is projected to increase by 900,000 to an average of 30.1m barrels per day in 2016, the report said. That's up from 29.2m in 2015.
Oil prices fell below $50 per barrel last week, hitting a new six month low, due to a resurgence of US production and rising Opec output. Signals of a boost in demand in Asia weren't enough to raise prices significantly.
Read more: Brent crude oil falls towards $49 a barrel
The market report said:
This decline in oil prices came amid a sell-off in crude futures, triggered largely by continued oversupply at a time when incremental global demand has not followed suit.
Financial concerns in Greece and China, as well as the outcome of the P5+1 talks on Iran’s nuclear programme, have all contributed to the current bearish market conditions.
Given the better-than-expected growth in global oil demand so far this year, together with some signs of a pick-up in the economies of the major consuming countries, crude oil demand in the coming months should continue to improve and, thus, gradually reduce the imbalance in oil supply-demand fundamentals.