OPEC crude production fell 640,000 barrels per day in August to 19.71 million bpd, a Reuters survey found, as Saudi export disruptions and a U.S. blockade of Iran overrode a planned OPEC+ supply increase.

The 11-member group planned to add barrels under an agreement reached by seven OPEC+ members, including Russia. The Middle East conflict made that volume unavailable, the survey showed. Saudi Arabia faced fresh export disruptions that the survey links to the war in Iran. The U.S. blockade cut Iran's own shipments.

How steep is the August drop?

The 640,000 bpd month-on-month decline erased any chance of the targeted increase reaching the market. The survey pegged the 11-member group at 19.71 million bpd for August.

The size of the cut shifted the OPEC+ signal from a planned step-up to a physical contraction. The market now has to parse a deficit where the cartel had signalled an addition.

What data fed the estimate?

The Reuters survey draws on:

• Flow data from financial information group LSEG
• Shipment tracking from Kpler
• Information from sources at oil companies, OPEC and consultants

That methodology gives a flow-based snapshot rather than direct national reporting. OPEC's own monthly market report, due in September, relies on secondary sources with similar limitations. The two series cover the same group but use different input sets, which is why country-level lines can diverge.

Which producers drove the decline?

The survey pointed to two named drivers: Saudi Arabia, where export flows faced fresh disruption linked to the war in Iran, and Iran itself, where a U.S. blockade cut shipments. The combined effect overrode any incremental volume the seven OPEC+ members could have contributed under the August plan.

Saudi export disruptions are a key driver of the loss. The war in Iran is the trigger the survey cites. Iran's removal of supply through the U.S. blockade compounds the picture.

Why does the missed hike matter for supply?

Seven OPEC+ members had agreed to raise output in August. None of that incremental volume reached the market. Saudi export disruptions and the U.S. blockade of Iran removed physical barrels the cartel had committed to add.

The 640,000 bpd net decline against a planned increase turns the August picture into a deficit relative to the policy roadmap. Crude buyers now face tighter availability from two key Middle East suppliers at the same time.

What does the OPEC+ signal mean now?

OPEC+ built its August roadmap on a coordinated step-up by seven members. The actual outcome inverts that policy without a formal reversal. The market has to distinguish between the cartel's stated intent and the physical reality on the docks and at the loading points.

The September OPEC+ meeting will offer the next formal read on whether the seven members renew the increase or pause. Compliance and conflict exposure will both sit on the agenda. The cartel now faces a choice between reaffirming the volume plan or acknowledging the physical ceiling.

What comes next on the watch list?

OPEC's monthly oil market report will publish the cartel's official August figures and give a country-level view. Any divergence from the Reuters survey on national output will force a re-pricing of compliance.

Watch item: the duration of the U.S. blockade of Iran and the pace of Saudi export restoration will determine whether 19.71 million bpd holds into September or slips further.