LONDON - Eastbound gas flows via the Yamal-Europe pipeline to Poland from Germany rose on Tuesday while nominations for Russian gas flows into Slovakia from Ukraine via the Velke Kapusany border point remained steady, operator data showed.

Exit flows at the Mallnow metering point on the German border stood at 4,527,661 kWh/h on Tuesday versus levels around 3,400,000 kWh/h the previous day, data from pipeline operator Gascade showed.

Nominations for Russian gas flows into Slovakia from Ukraine via the Velke Kapusany border point were at around 36.9 million cubic metres (mcm) per day, unchanged from the previous day, data from the Ukrainian transmission system operator showed.

Physical flows and nominations via the Nord Stream 1 pipeline remain at zero due to maintenance that is scheduled to end on July 21.

Russia's Gazprom has told customers in Europe it cannot guarantee gas supplies because of "extraordinary" circumstances, according to a letter seen by Reuters, adding to fears in Europe that Moscow may not restart the pipeline at the end of the maintenance period in retaliation for sanctions imposed on Russia over the war in Ukraine.

Gazprom said its supply of gas to Europe through Ukraine via the Sudzha entry point was expected at 41.7 million cubic metres (mcm) on Tuesday, compared with 41.5 mcm a day earlier.

(Reporting by Marwa Rashad; Editing by Kirsten Donovan)