Vertical Gas Corridor is being developed from an initial response to disrupted Russian supplies into a broader infrastructure and market-integration effort connecting southern Europe with Ukraine and central European gas hubs. Transmission system operators from nine countries are now involved. Greece, Bulgaria, Romania, Moldova and Ukraine are joined by Serbia, North Macedonia, Hungary and Slovakia, extending the corridor’s geographic reach.
Athens working group to align cross-border operations
In Athens, the operators agreed to set up a working group focused on integrating the Serbian and North Macedonian networks. The work will cover technical, regulatory and operational requirements. The immediate task goes beyond reserving cross-border capacity and includes aligning operating rules, nomination procedures, tariffs and gas-quality standards across systems built around different supply routes.
From LNG alternative to broader southeast European gas architecture
The corridor was first promoted as an alternative route for transporting gas northwards from Greek LNG terminals after Russian transit through Ukraine was reduced. It is now being positioned as a permanent part of southeast Europe’s gas architecture. The project is described as providing access to LNG, Azeri gas and potentially other non-Russian supplies.
Greece has become the principal southern entry point for the corridor. Its export capacity increased from approximately 1 billion cubic metres in 2021 to around 9 billion cubic metres, supported by LNG infrastructure and improvements to neighbouring transmission systems. Additional capacity is expected when the Greece–North Macedonia interconnector enters operation, currently forecast for the end of 2027.
Serbia integration and next commercial milestones
Serbia’s participation is intended to strengthen the corridor’s western Balkan dimension. The country sits between Bulgaria and Hungary and the former Yugoslav markets, while its gas system has historically been oriented toward Russian supply delivered via the Balkan Stream route. Connecting Serbia more effectively with Greece would add supply optionality, with commercial outcomes tied to competitive transmission tariffs and firm capacity across multiple borders.
The next practical milestone is the auction of three-month transmission products in August 2026. After that auction, the nine operators are expected to sign a memorandum in September formally incorporating Serbia and North Macedonia into the initiative. The corridor’s relevance is also increasing as the European Union targets ending remaining Russian gas imports by autumn 2027.
Poland and Slovakia have expressed interest in closer participation through the Central and South Eastern Europe Energy Connectivity framework . Infrastructure development alone is not described as sufficient for commercially viable flows. The route crosses multiple tariff zones, where accumulated transmission charges can make LNG delivered through Greece more expensive than alternatives arriving from central Europe.
Long-term value is therefore linked to coordinated capacity products, tariff reform and enough contracted demand to support continuous rather than occasional gas movements .
