Germany has temporarily reintroduced border controls, acknowledging it can scarcely cope with the daily influx of thousands of asylum seekers.
Thomas de Maiziere, Germany's interior minister, said the move was an attempt to reduce the number of asylum seekers arriving in the country.
"At this moment Germany is temporarily introducing border controls again along [the EU's] internal borders. The focus will be on the border to Austria at first," he said.
"The aim of these measures is to limit the current inflows to Germany and to return to orderly procedures when people enter the country," he said, adding that this was also necessary for security reasons.
The first reported indications of the move came when German authorities halted train traffic from Austria on Sunday.
"No more trains will run from Austria to Germany," a spokeswoman for Austrian rail company OeBB said. "The Germans will not take over any trains."
The change in policy came amid comments by economy minister Sigmar Gabriel that Germany had reached its limits over the refugee crisis, about a week after Germany effectively opened it borders to asylum seekers.
The move made Germany, Europe's strongest economic power, a magnet for many people fleeing war and poverty in Syria and other parts of the Middle East, Asia and Africa.
German authorities said that on Saturday alone about 13,000 migrants arrived in the southern city of Munich, in Germany's Bavaria region, and another 3,000 on Sunday morning.
Horst Seehofer, the Bavarian premier, said the border controls would remain in place until the situation improved. He also said that while they were limited to Austria for the time being, but could be extended to other countries if necessary.
A European Commission statement appeared to quash concerns the reintroduction of border controls might violate Schengen Area rules, saying: "The current situation in Germany, prima facie, appears to be a situation covered by the rules."
Schengen Area members are allowed to reimpose border controls during crisis situations.