The Organisation of Petroleum Exporting Countries (Opec) said, despite the recent fall in oil prices, refining margins weakened last month due to a glut of oil products such as petrol. This was driven by a smaller-than-expected increase in seasonal demand.
"There are lingering concerns that the US and European refiners could cut runs in response to a declining gasoline crack in both regions in a period when summer driving and margins should have been at their highest during the year," according to Opec's monthly report released today.
"This has been the major factor contributing to the downward pressure on crude prices in recent weeks."
Concern that the oil market is recovering at a slower pace than previously expected has weighed on crude prices. Rising US oil stocks and a glut of oil products sent the black stuff to a three-month low recently.
The average price of crudes from Opec producers fell for the first time in five months, averaging $42.68 last month compared to $45.84 in July, according to the report.
This was due to "less-than-anticipated demand, high stocks, particularly of refined products, and rising supply".
"Hedge funds have also turned more negative, contributing to further pressure on oil prices," it said.