Investing.com -- OPEC crude production fell in May to its lowest level in at least 37 years as a US blockade of Iran and disruptions in the Persian Gulf continued to limit output, according to a Bloomberg survey released Friday.

Output from the organization's 11 current members dropped by 1.22 million barrels per day to 16.33 million barrels per day last month. Iran accounted for more than half of the decline. The data excludes the United Arab Emirates, which departed the Organization of the Petroleum Exporting Countries last month after six decades of membership.

War between a US-Israeli alliance and Iran has reduced oil supplies from the Middle East, largely closing the Strait of Hormuz waterway. Saudi Arabia, Iraq, the UAE and Kuwait have been forced to cut crude production. Iranian shipments face additional pressure following a US blockade of its ports imposed in mid-April.

Iranian output fell by 710,000 barrels per day to a five-year low of 2.34 million barrels per day in May, the survey showed. Central Command reported US forces have redirected 127 commercial vessels to enforce the blockade of all maritime traffic entering and exiting Iranian ports.

Kuwait recorded the second-largest decline last month, with production falling by 310,000 barrels per day to 490,000 barrels per day, less than one-fifth of pre-war levels. Saudi Arabia, the group's leader, saw output decrease by 240,000 barrels per day to 6.57 million barrels per day.

The production reductions have not prevented OPEC and its allies from raising quotas over recent months, continuing a year-long process of restoring output halted several years ago.

Three OPEC+ delegates said they expect key members to increase targets by 188,000 barrels again in July during a video conference on Sunday. The session is one of four online meetings OPEC and its partners plan to hold that day.

Delegates indicated the alliance has plans for two additional monthly quota increases in August and September. UAE output rose by 300,000 barrels per day to 2.44 million barrels per day in May, according to the survey.