Russian energy giant Gazprom's average daily natural gas supplies to Europe via the TurkStream undersea pipeline decreased by 18.3% in June compared to the previous month, according to Reuters calculations released Wednesday. 

The decline is attributed to ongoing maintenance on the critical infrastructure.

Turkey remains the sole transit route for Russian gas to Europe after Ukraine opted not to renew its five-year transit agreement with Moscow in January.

Data from the European gas transmission group Entsog showed Russian gas exports through TurkStream dropped to 37.6 million cubic meters per day in June, down from 46 mcm per day in May. This also marks a decrease from the 39.5 mcm shipped via the route in May 2024.

Despite the June dip, Russian gas supplies to Europe via TurkStream saw an increase of approximately 6.8% in the first half of this year compared to 7.8 billion cubic meters during the same period a year earlier, Reuters calculations revealed.

Overall, total Russian gas exports to Europe from January to June fell to 8.33 billion cubic meters, a significant drop from 15.5 bcm in the year-earlier period, factoring in supplies that previously transited through Ukraine.

Gazprom, which has not released its own monthly statistics since early 2023, did not respond to a request for comment.

Russian gas flows to Europe have seen a dramatic decline in recent years. After peaking at between 175 bcm and 180 bcm annually in 2018-2019, supplies via various routes plummeted by 55.6% from 63.8 bcm in 2022 to 28.3 bcm in 2023. In 2024, the gas supplies saw a modest increase to around 32 bcm.