By Kirsti Knolle

SALZBURG, Austria (Reuters) - Germany on Wednesday closed a rail link that has brought tens of thousands of migrants onto its territory from Austria in less than two weeks, prompting hundreds of people to walk across its border rather than wait for trains.

The flow of trains carrying migrants into Germany through the Austrian city of Salzburg had already been severely disrupted by German border checks introduced on Sunday and the connection was cut completely on Wednesday.

After hours of waiting in Salzburg's main station, hundreds set off on foot for Germany, roughly 8 km (5 miles) away.

German police said they had received no warning about the approach of such a large crowd.

"The situation is very tense," said a police spokesman in Rosenheim, on the German side of the border, where he said 700 migrants had arrived. About 700 more people were expected to arrive soon, he added.‎

In Salzburg, most of the migrants who had been waiting at the station left in the course of the morning as they realised there would be no trains, officials said.

"We had more than 2,000 refugees an hour ago. The station was about to be closed," Wilfried Haslauer, the governor of Salzburg province, said on Wednesday morning.

A spokesman for the city of Salzburg, Johannes Greifeneder, said Germany would have "a much bigger problem" monitoring and registering refugees arriving by foot instead of by train.

Rail traffic between Germany and Salzburg was halted in both directions on orders of the German authorities, a spokeswoman for the Austrian rail operator OeBB said, adding that no details on the reason for the closure were immediately available.

Migrants have poured into Austria since it and Germany said more than a week ago that they would open their borders to crowds trekking through the Balkans and across Hungary in Europe's biggest migration crisis in decades.

Germany, the intended destination of most migrants, moved earlier to introduce border checks as it struggled to cope with the influx. For days, migrants arrived in Austria faster than they could enter Germany and their numbers grew.

NEW WAVE

With much of its emergency accommodation already crowded, Austria was preparing for another wave of refugees to arrive, and extended border checks to its southern flank in the hope of slowing them.

The police said they were expecting migrants to try to work their way around Hungary's newly barricaded southern border and head northwest through Croatia and Slovenia. The rush from Hungary has slowed dramatically since Tuesday, when the Hungarian authorities fenced off their border with Serbia.

As a result, Austria was extending its own toughened border checks - which were modelled on Germany's and introduced on the border with Hungary on Wednesday morning - to its frontier with Slovenia, to the south, an Interior Ministry spokesman said.

The police in the Austrian province of Styria, which borders Slovenia, said they were preparing to put the controls in place even though they did not appear necessary for the time being.

"Until now, not a single refugee has come across the border," a Styrian police spokesman said.

"We have information from Serbia that several thousand people are waiting there to travel over the Croatian border into the EU area," he added.

Austria has made clear that its border controls are aimed at slowing migrants rather than turning them away altogether, but the moves have effectively suspended a system of borderless travel within Europe known as Schengen.

"These border controls should be an important signal to the world," Interior Minister Johanna Mikl-Leitner told the broadcaster ORF late on Tuesday. "There can be no borderless flow of migrants."

Austria and Germany have called for a European leaders' summit to address the migration crisis, Europe's worst since the wars in the Balkans in the 1990s, and called for binding quotas for the redistribution of asylum seekers within the EU, combined with stricter measures near its external border.

The proposals have faced opposition from Eastern European countries.

Austrian Chancellor Werner Faymann has arranged meetings with his Croatian, Slovenian, French and Swedish counterparts as well as the German vice chancellor in the coming days in an apparent effort to build support for the plan.

(Additional reporting by Francois Murphy, Shadia Nasralla and Alexandra Schwarz-Goerlich in Vienna, and Anna McIntosh in Nickelsdorf, Austria; Writing by Francois Murphy; Editing by Gareth Jones)