"Greece is going to ask the international court in The Hague to investigate crimes of war conducted in Mariupol," Foreign Minister Nikos Dendias said as he arrived for the second day of a NATO meeting on the war in Ukraine.

"Greece has a specific, special interest for Mariupol because of the existence of a 100,000 and more Greek community in Mariupol," he said.

The ICC's chief prosecutor said a month ago the court had opened "active investigations" into possible war crimes in Ukraine, backed by dozens of countries.

Mariupol, located in a strategic southeastern spot between Russia-occupied Crimea and pro-Russian separatist regions in Ukraine's east, has been the scene of some of the fiercest assaults by Moscow's forces.

Residents spoke of utter devastation and dire conditions in the city, where the population has shrunk from 400,000 before the war to around 120,000.

Dendias said he was going to ask NATO allies to do "our best" to help another, bigger strategic port city, Odessa, withstand Russian attacks.

To do that, he said, "is quite simple: by giving to Ukraine the adequate means to protect the city they have asked for it already".