Speaking during a televised debate of political leaders, Mitsotakis said he had faced an "exceptionally aggressive" Turkey during his four-year term.

The outgoing premier pointed to Turkey's so-called "Blue Homeland" strategy of staking out claims to energy resources in the eastern Mediterranean.

Turkish President Recep Tayyip Erdogan last year repeatedly accused NATO ally Greece of "occupying" Aegean islands whose status was settled in post-war treaties and warned that Turkey's armed forces could "come overnight" and "do what is necessary".

A frontrunner in opinion polls, Mitsotakis on Wednesday said he would extend a "hand of friendship" to whoever emerges as leader from May 14 elections in Turkey.

But he said he was under no "delusions" about the need to build strong defensive alliances with other NATO allies such as the United States and France.