The Yamal-Europe pipeline, which usually sends Russian gas west into Europe, flowed east from Germany to Poland for a 25th successive day on Friday, data from German network operator Gascade showed.
Since Dec. 21, the link between Poland and Germany had been operating in reverse mode, putting upward pressure on European gas prices, Reuters reported.
The pipeline usually accounts for about one-sixth of Russia's annual gas exports to Europe and Turkey.
Eastbound volumes stood at 7.2 million kilowatt hours per hour (kWh/h), down from more than 8 million kWh/h earlier this week, and are expected to remain in reverse until the early hours of Saturday, data from the Mallnow metering point on the German-Polish border showed.
It is not clear when the pipeline will revert to westbound flows into Germany.
A source close to Gazprom said the company is expected to switch flows at some point this month, as Gazprom has paid for westbound volumes.
Capacity nominations for Russian gas flows from Ukraine to Slovakia via the Velke Kapusany border point, another major route for Russian gas to Europe, stood at 287,927 megawatt hours (MWh) on Friday.
That is the lowest level since Sunday and well below levels of more than 900,000 MWh recorded in early December, data from Slovak pipeline operator Eustream showed.