The Vertical Gas Corridor is developing from a short-term response to disrupted Russian supplies into a broader infrastructure and market-integration project linking southern Europe with Ukraine and central European gas hubs.
Transmission system operators from nine countries are now involved. Greece, Bulgaria, Romania, Moldova and Ukraine have been joined by Serbia, North Macedonia, Hungary and Slovakia, materially extending the corridor’s geographic reach and its potential commercial value.
At a meeting in Athens, the operators agreed to establish a working group that will examine the technical, regulatory and operational requirements for integrating the Serbian and North Macedonian networks. The immediate challenge is not simply to reserve cross-border capacity, but to align operating rules, nomination procedures, tariffs and gas-quality standards across systems that were designed around different supply routes.
The corridor was initially promoted as an alternative route for transporting gas northwards from Greek LNG terminals following the reduction of Russian transit through Ukraine. It is now being positioned as a permanent component of southeast Europe’s gas architecture, providing access to LNG, Azeri gas and potentially other non-Russian supplies.
Greece has become the project’s principal southern entry point. Its export capacity has 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. Further capacity should become available when the Greece–North Macedonia interconnector enters operation, currently expected by the end of 2027.
Serbia’s participation could strengthen the corridor’s western Balkan dimension. The country occupies a central position between Bulgaria, Hungary and the former Yugoslav markets, but its gas system has historically been oriented towards Russian supply delivered through the Balkan Stream route. Connecting Serbia more effectively with Greece would provide additional supply optionality, although the commercial benefit will depend on competitive transmission tariffs and the availability of firm capacity across several borders.
The next practical milestone will be the auction of three-month transmission products in August 2026. The nine operators are then expected to sign a memorandum in September formally incorporating Serbia and North Macedonia into the initiative.
The corridor’s relevance is increasing as the European Union works towards ending remaining Russian gas imports by autumn 2027. Poland and Slovakia have also expressed interest in closer participation through the Central and South Eastern Europe Energy Connectivity framework.
Infrastructure alone will not guarantee commercially viable flows. The route crosses multiple tariff zones, and accumulated transmission charges can leave LNG delivered through Greece more expensive than alternatives arriving from central Europe. Its long-term value will therefore depend on coordinated capacity products, tariff reform and enough contracted demand to support continuous rather than occasional gas movements.
