Slovakia has long relied on Russian gas, with 85% of imports coming from Russia in 2021. According to the Warsaw-based Centre for Eastern Studies (OSW), diversification efforts cut this to 50% by 2023, but Slovakia remains among Europe’s most dependent on Russian energy.

Bratislava, which has a long-term contract with Russia's Gazprom, has sought to retain gas flows through Ukraine although Kyiv has refused to extend a transit deal with Moscow because of the ongoing Ukraine war.

Lukáš Vlček, the Czech energy minister, has written to his Slovak counterpart to say the Czech Republic could provide additional capacity, both in this heating season and on a long-term basis, the ministry said.

Vlček said alternative supplies to the region would become more affordable after Germany agreed to exempt countries transiting gas from a domestic gas levy from January 1.

The Czech Republic is among the European countries that no longer buys gas directly from Russia, but the cost of the German levy had made it rely increasingly on cheaper gas via Slovakia, potentially of Russian origin, in recent months.