Turkish President Recep Tayyip Erdogan has said he no longer recognises the leader of neighbouring Greece and will refuse to meet him at a planned summit.
Mr Erdogan accused Greek Prime Minister Kyriakos Mitsotakis of seeking to block the sale of American-made F-16 fighter jets to Turkey while visiting the US.
"There's no longer anyone called Mitsotakis in my book," Mr Erdogan told reporters after a cabinet meeting.
Greece said it would not get into a "confrontation of statements".
The row comes amid Turkey's threats to block a proposed expansion of NATO.
