The Ukrainian operator's data showed that 41.6 million cubic meters of gas are expected to be moved from Russia to Europe via Ukraine on Thursday.
Gazprom said it would send 39.4 million cubic metres (mcm) of gas to Europe via Ukraine on Wednesday, down from 42.4 mcm on Tuesday.
The Ukrainian transit operator said earlier on Wednesday that Russian natural gas continued to transit Ukraine as normal despite reports of clashes near the Russian town of Sudzha where Russian gas flows into Ukraine.
Currently, about 42 million cubic metres of gas passes through Sudzha every day. The total annual transit volume is about 14 billion cubic metres.
"As of 1300 Kyiv time (1000 GMT), gas is being transported to European customers as usual, without any changes. Nominations have been confirmed and the physical flow of gas is maintained," the operator told Reuters.
The Russian defence ministry said on Wednesday its forces had thwarted an advance of Ukrainian troops deep into the border area in the western Russian region of Kursk.
Two Russian military blogs said, without providing evidence, that Ukrainian forces had captured a gas measuring facility at Sudzha, through which Russian natural gas passes.
Reuters could not independently verify the situation on the ground.
The Sudzha gas transfer and measuring stations in the Kursk region of Russia are the only entry point for Russian natural gas into the Ukrainian gas transmission system for onward transport to Europe.
In May 2022, at the beginning of the Russian invasion of Ukraine, the Ukrainian transit operator stopped transporting gas on an alternative branch line through the transit point of Sokhranivka close to the Luhansk region in the east.
Ukraine said Russian forces had started taking gas transiting through Ukraine and sending it to two Russia-backed separatist regions in the country's east.
After the closure of Sokhranivka, transit volumes fell by a quarter as Gazprom said it was unable to divert volumes to Sudzha.
The agreement on Russian gas transit to Europe through Ukraine expires in 2024, and Kyiv has said it has no intention of extending it or concluding a new deal.
