Austria has said it is planning to construct a fence at the main border crossing used by migrants entering the country from Slovenia.
Austrian Chancellor Werner Faymann said the move would not shut the border, but would allow better control of arrivals.
It came as Germany said it expected the number of deportations of failed asylum seekers to rise.
Meanwhile, at least three migrants drowned and 242 were saved when a boat sank off the Greek island of Lesbos.
"We do not have a picture of how many people may be missing yet," a Greek coastguard spokeswoman said.
Earlier, three migrant boats were reported to have capsized between Turkey and the Greek islands amid worsening weather in the area.
BBC Europe correspondent Damian Grammaticus says Austria and Germany, the two countries at the heart of Europe's refugee crisis, seem to be toughening their tone.
They appear to be trying to deter refugees from setting out on their journeys and to head off political critics at home, he adds.
The UN estimates more than 700,000 migrants have crossed to Europe by boat so far this year - mainly from war-ravaged Syria. The approach of winter has so far done little to slow the flow.