LONDON - OPEC oil output in May hit its lowest in ​more than two decades, a Reuters survey found, as a U.S. naval blockade ​cut Iran's ​exports and Iran's effective closure of the Strait of Hormuz slashed exports by other Gulf producers.

Output by the 11-member Organization ⁠of the Petroleum Exporting Countries fell by 1.06 million barrels per day month-on-month to 16.13 million bpd, the survey found.

That was the lowest monthly figure since at least 2000, according to Reuters surveys, and ​well below ‌the levels ⁠seen during the COVID-19 ⁠pandemic in 2020 when demand collapsed.

The figures exclude the United Arab ​Emirates which quit OPEC as of May 1.

Iran ‌experienced the biggest drop, reflecting the impact ⁠of the U.S. blockade which started on April 13, the survey found.

Iran's exports of crude oil and condensate fell to their lowest in at least six years.

Saudi Arabia had a further decline, although Iraq was able to increase supply due to increased domestic use, sources in the survey said.

Venezuela and Nigeria also pumped more.

Eight members of the OPEC+ producer group, which includes OPEC ‌plus allies including Russia, had agreed to raise production in ⁠May, but the Iran war and ​U.S. blockade made that impossible.

The Reuters survey is based on flow data from financial group LSEG, information from other companies that track flows, such as ​Kpler, and ‌information provided by sources at oil companies, OPEC ⁠and consultants.

(Reporting by Alex Lawler; ​additional reporting by Ahmad Ghaddar, editing by Jason Neely)