European Council President António Costa urged Western Balkan countries to accelerate reforms and seize what he described as a renewed opportunity for European Union enlargement during a regional tour ahead of a summit in Montenegro later this week.

Costa's four-day visit, which began in Bosnia & Herzegovina and continued in Albania, takes place as Brussels seeks to maintain momentum in its long-stalled expansion policy amid heightened geopolitical tensions and Russia's continuing war in Ukraine.

"My visit to the region sends a clear signal: our commitment to the Western Balkans is real, and so is the opportunity of enlargement. The momentum is there. Now is the time to deliver," Costa said in a statement released at the start of the tour.

The former Portuguese prime minister is visiting all six Western Balkan partners before co-chairing an EU-Western Balkans summit in the Montenegrin coastal city of Tivat on June 5, focused on what organisers describe as the "shared prosperity and stability" of the region and the bloc.

In Sarajevo on May 31, Costa praised progress made by Bosnia but warned political leaders that accession prospects depended on completing long-delayed reforms.

"Bosnia and Herzegovina needs to decide if it will do the necessary work to share the same future in the European Union," Costa said after meeting members of the country's tripartite presidency.

"You are only a few steps away from the next tangible phase in the opening of accession negotiations – now is the time to focus on your goal and accelerate the pace of reforms."

He urged Bosnian leaders to approve two outstanding judicial reforms, appoint a chief negotiator for EU talks and implement the country's Reform Agenda, warning that delays could jeopardise substantial EU funding.

"Bosnia and Herzegovina has already lost €108mn and an additional €373mn are at risk in the coming months," Costa said.

The EU has sought to use its €6bn Reform and Growth Facility for the Western Balkans to encourage economic and governance reforms while bringing the region closer to the bloc's single market before full membership.

In Tirana on June 1, Costa hailed Albania's recent progress after EU member states last week confirmed that the country had met interim benchmarks under the "fundamentals" cluster of accession negotiations.

"Albania is making fast and concrete progress towards EU accession. Now is the time to further advance on the path towards enlargement," Costa said.

Speaking alongside Prime Minister Edi Rama, Costa said the latest accession conference represented "a clear recognition by the member states of Albania's commitment to further advance on the path towards membership of the European Union."

However, he stressed that difficult work remained ahead. "Continued, tangible political commitment to the rule of law and in safeguarding an independent and accountable judiciary are essential foundations for EU membership. I encourage you to step up the efforts in fighting corruption and organised crime," he said.

The Western Balkans are now higher on the EU agenda as policymakers increasingly frame enlargement as a strategic necessity rather than simply a technical accession process.

Costa repeatedly linked expansion to broader security concerns, arguing that integrating the region would strengthen Europe's resilience during a period of global instability.

"In this time of global geopolitical uncertainty and economic instability, more than an opportunity, enlargement is also a geostrategic necessity for Europe. It is an investment in the peace, stability and security of our continent," he said in Tirana.

He used similar language in Sarajevo, describing enlargement as "a geostrategic interest for Europe”. 

The renewed emphasis on enlargement reflects growing concern in Brussels about external influence in the Western Balkans from Russia, China and other powers, as well as fears that prolonged delays could undermine public support for EU integration across the region.

The bloc has recently sought to demonstrate tangible benefits of closer integration before membership, including access to the Single Euro Payments Area (SEPA), lower roaming charges and gradual participation in the EU single market. Costa pointed to Albania's participation in initiatives such as SEPA and the EU's roaming arrangements as examples of the benefits already available to candidate countries.

The European Council president said the June 5 summit in Tivat would demonstrate the determination of both sides "to bring forward our cooperation and build on the momentum of the European Union's enlargement.” Costa's tour will continue with visits to North Macedonia, Kosovo and Serbia before the summit opens on June 5.