Greece said on Thursday it was possible that large groups of refugees from Syria may be about to seek entry into the country from its land border with Turkey.
This would be a relatively new entry point to Greece for the refugees, tens of thousands of whom have braved small boats and sometimes dangerous seas this summer to get from Turkey to Greek islands such as Kos and Lesbos and onwards into the European Union.
"From our side, we are preparing for a possible new wave from the Evros border," said Rodolphos Moronis, spokesman for Greece's pre-election caretaker government.
The Evros river divides Greece from Turkey in the far northeast, south of Bulgaria.
Moronis said there was no international agreement with Turkey to prevent refugees passing through the border.
About 30,000 people, mainly fleeing the war in Syria, were shipped to the Greek mainland last week, mainly arriving in Piraeus, west of Athens.
Like others, they nearly all moved north through the Balkans, hoping to reach Germany or other wealthy northern EU countries.
One of the Greek ships being sent in a relay by the government to collect people from Lesbos docked at Piraeus on Thursday with 1,986 migrants on board.
Two other boats were en route, according to the maritime website marinetraffic.com.
"We need to have a good life, you know. We have a lot of educated people, qualified people, but we have no chance to live in Syria anymore," said one refugee arriving in Piraeus, who described himself as a professor from Aleppo, in Syria.
Some countries, notably Hungary, have closed their borders to the refugees, threatening a backup into other countries, including Greece.
That was not lost on at least one of Thursday's arrivals in Piraeus.
"I don't how we can go to Germany, because Hungary has closed the door," said Zia, a Syrian from Kobani.