Any European Union decision to sanction Turkey over its standoff with Greece is not a big concern, President Recep Tayyip Erdogan said on Wednesday, a day before EU leaders meet for a summit.

Turkey, an EU candidate whose accession has been frozen over issues including its human rights record, is at odds with Greece over maritime and energy rights in the eastern Mediterranean.

"Turkey does not care much about any sanctions decision to be made by the EU," Erdogan said in a televised press conference at an Ankara airport before leaving for Azerbaijan.

"The EU has never treated us honestly. The EU has never stood by any promise it has given us but we always remained patient and we are still patient," he said.

Ankara has angered Greece and the rest of the EU by sending a survey ship and navy vessels to the disputed waters in defiance of calls to stop. It ordered the Oruc Reis ship back to port last month.

Athens is now pressing for punitive sanctions against Turkey at the EU summit beginning on Thursday.

France supports Greece's call for sanctions but not all countries are convinced, with some fearing an influx of refugees from Turkish territory.

Erdogan said "sincere and honest" leaders in the EU were not warm to the idea of sanctions, without naming them.