LONDON - OPEC oil output fell in May after Saudi Arabia and other members of the OPEC+ alliance made voluntary output cuts to support the market, a Reuters survey found on Wednesday, although increases elsewhere in the group limited the decline.

The Organization of the Petroleum Exporting Countries has pumped 28.01 million barrels per day (bpd) this month, the survey found, down 460,000 bpd from April. Output is down more than 1.5 million bpd from September.

The survey aims to track supply to the market. It is based on shipping data provided by external sources, Refinitiv Eikon flows data, information from companies that track flows such as Petro-Logistics and Kpler, and information provided by sources at oil companies, OPEC and consultants.

(Additional reporting by Ahmad Ghaddar Editing by Kirsten Donovan)