Greece warned on Tuesday that it would not allow the illegal entry of migrants by land or by sea, after a sharp increase in attempted entries through its Aegean islands and land border with Turkey over the past few days.
The Mediterranean country was the frontline of Europe's migration crisis in 2015 and 2016 when a million refugees fleeing war and poverty from Syria, Iraq and Afghanistan arrived, mainly via Turkey.
The number of arrivals had fallen sharply since then, but in recent weeks, Greek authorities said they had stopped a significant number of people from entering.
About a dozen vessels with hundreds of migrants on board have attempted unsuccessfully to cross from Turkey's coast to the Greek islands in the past 48 hours, according to police data. On Tuesday, the coast guard said more than 590 people had tried to cross into the country by sea within a few hours.
"We won't allow anyone to enter Greece illegally either from Evros or through the islands. Let everyone realise this," Civil Protection Minister Takis Theodorikakos said on the Greek ANT1 TV channel.
Theodorikakos was speaking a day after Turkish President Tayyip Erdogan accused the Greek prime minister of trying to block sales of F-16 fighter jets to Turkey during a visit to the United States. "He no longer exists for me," Erdogan said.
Greece and Turkey, NATO allies and historic rivals, have long been at odds over migrant issues and competing territorial claims in the eastern Mediterranean.
About 11,000 migrants entered Greece through the Greek-Turkish land border in the region of Evros or through the Aegean islands in the first four months of the year, 25% higher than a year ago, according to government data.
(Reporting by Lefteris Papadimas; Editing by Bernadette Baum)