The Organization of the Petroleum Exporting Countries has pumped 27.90 million barrels per day (bpd), the survey found, up by 180,000 bpd from September. Production in August had risen for the first time since February.

The steady rise in OPEC output is largely being driven by a small number of producers managing to overcome internal or external factors that have curbed supply, such as U.S. sanctions or unrest. Despite the rise in output, oil prices are finding support from conflict in the Middle East.

Nigeria boosted exports in October without any major disruption to shipments, according to shipping data and sources in the survey, increasing output by 50,000 bpd. The country is targeting a further recovery by next year. Angola also boosted exports in October, the survey found.

Smaller increases came from Iraq and Iran. Tehran's output edged up to 3.17 million bpd, the survey found. This is the highest since 2018, the year Washington re-imposed sanctions on Iran, according to Reuters surveys and OPEC figures.

Analysts have said the higher Iranian exports appear to be the result of Iran's success in circumventing U.S. sanctions.

There was no immediate boost in Venezuela's production, sources in the survey said, following the U.S. move this month to broadly ease sanctions on the country's oil sector. OPEC+ sources expect the production recovery to be gradual.

Output from the 10 OPEC members that are subject to OPEC+ supply cut agreements rose by 150,000 bpd, the survey found. Saudi Arabia and other Persian Gulf members maintained strong compliance with agreed cutbacks and extra voluntary reductions.

Saudi Arabia kept October and September output close to 9 million bpd, the survey found. The country in September extended a voluntary 1 million bpd output cut until the end of the year to provide extra support for the market.

OPEC's output is still undershooting the targeted amount by about 560,000 bpd, mainly because Nigeria and Angola lack the capacity to pump as much as their agreed level.

The Reuters survey aims to track supply to the market. It is based on shipping data provided by external sources, LSEG 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.