Under the Athens Declaration, signed in the presence of Ukraine's President Volodymyr Zelensky, the countries expressed their "unwavering support for Ukraine's independence, sovereignty and territorial integrity within its internationally recognized borders, based on the values of democracy and rule of law" in the face of Russia's aggression.

Apart from Ukraine, the document was signed by the leaders of Serbia, Moldova, Montenegro, Romania, Kosovo, Bosnia and Herzegovina, North Macedonia, Bulgaria and Croatia, as well as Greece which was hosting the event, in the presence of the European Council President Charles Michel and the European Commission President Ursula von der Leyen.

The leaders also expressed their "support and appreciation for the earnest efforts by Ukraine's President Volodymyr Zelensky in setting out the principles for peace in line with the UN Charter, in his Peace Formula."

They committed "to support Ukraine and Moldova to take the next steps in their accession process as soon as they have completed the necessary reforms."

Greek PM Kyriakos Mitsotakis's office said the gathering marked the twentieth anniversary of the 2003 Thessaloniki summit confirming the European perspective of Western Balkan states.

Zelensky visited Athens to attend the informal meeting, concluding a European tour with previous stops in Sweden, the Netherlands and Denmark.

Greece has said it will help train Ukrainian F-16 warplane pilots and assist the reconstruction of Odesa.

Kyiv on Friday welcomed a US decision to let Denmark and the Netherlands hand F-16 fighter jets over to Ukraine once its pilots are trained to use them.