European Union governments agreed on Thursday to step up deportations of illegal immigrants and discussed creating an EU border force among measures to cope with hundreds of thousands of refugees from Syria's civil war.
Underlining the havoc brought by chaotic mass treks across Europe's open borders over recent months, the German state of Bavaria threatened to break ranks with Berlin and send back to Austria migrants who cross its Alpine frontier.
Chancellor Angela Merkel, whose welcome for refugees has taken a toll on her ratings, insists she will not shut the door.
Her deputy said there could be no pulling up of "drawbridges".
Austria's interior minister warned of possible border "riots".
The dispute between Vienna and one of Germany's richest regions, which says over 200,000 migrants entered from Austria in a month, helps explain Merkel's vocal support this week for the expulsion of those not fleeing for their lives and for tighter controls on who enters Europe across the Mediterranean.