Russia increased oil exports through its western ports by 15% in May compared to April, two industry sources familiar with the data said, Reuters reported.
Refinery outages caused by Ukrainian drone attacks are forcing Moscow to export more crude.
Ukraine has stepped up drone attacks on both refineries and oil export facilities this spring. This has led to fuel shortages in Russia and weighed on oil production.
According to the International Energy Agency, oil production in Russia fell in April.
Russian diesel production fell another 10% in May.
Intensified Ukrainian drone attacks on refineries have forced some facilities to reduce or completely stop operations.
May exports through the western ports of Primorsk, Ust-Luga and Novorossiysk increased to 2.5 million barrels per day from 2.2 million barrels per day in April, the sources said.
This is the largest amount exported from western ports since September 2025, when Ukrainian drone attacks again halted processing at Russian refineries.
The authorities have so far responded by banning the export of aviation fuel and plans to limit gasoline and diesel exports.
The higher crude oil exports allow Russia to avoid massive production cuts, the sources said. However, Russia's export capacity to the West is limited, making it difficult to absorb all the oil that is not being processed, they added.
Virtually all major oil refineries in central Russia have been forced to halt or reduce fuel production after Ukrainian drone attacks in recent days.
Exports increased in May despite ongoing drone attacks on Novorossiysk, which briefly halted loading. Ukraine also continued strikes on pipelines and pumping stations of "Transneft" last month.