Flows through a pipeline carrying crude from fields in the autonomous northern region to the Mediterranean port of Ceyhan were down from 457,314 bpd the previous month and the lowest since March's 327,371 bpd.
A ministry statement gave no explanation for the decline, and a spokeswoman did not immediately reply to a request for comment.
The statement said an additional 640,329 barrels provided by Iraq's state-owned North Oil Co were pumped to KRG storage in Ceyhan during August.
Baghdad and Erbil resumed jointly exporting crude from the giant Kirkuk oilfield after cutting a preliminary deal on revenue-sharing, trading sources said last week.
The Kirkuk flows, usually amounting to 150,000 bpd, had been suspended since March as the central government pushed Kurdistan to agree a new deal on sharing oil and budget revenues.
Net income received from August exports by the KRG was seen at about $349.9 million while the gross value realised for crude was about $414 million, the ministry said.
The average price per barrel was $32.44.