The measure will already affect migrants on board of the first train due from Croatia at 10 PM and security is being tightened on the green border, that is outside border crossings.

The measure comes after Austria decided to allow entry only to refugees seeking asylum in Austria or Germany and to limit the number of asylum applications it will accept this year.

The minister said that she briefed other members of the cabinet on measures taken by Austria, of which she had been informed on by her counterpart Johanna Mikl-Leitner.

Slovenia has already notified Croatia and other countries on the Balkan route of the measure.

"It's too early to say how Croatia will react, we'll wait until the measure comes into practice," the minister said in response to whether Croatia would accept the migrants turned back by Slovenia.

She hopes the new Croatian government will "tackle the migration issue more constructively". She expects agreements to be honoured and does not wish to see a repeat of "the policy of information blockade".

Asked what would happen to the migrants seeking asylum in Slovenia, the minister said the measure was not prejudging international protection procedures in Slovenia.

Slovenia will continue to honour its obligations in the field, she said, but could not yet say what would happen to the migrants not meeting the conditions for asylum.

The Interior Ministry will report on the implementation of restriction and details at a news conference on Friday. "The procedures at the moment are not much out of the ordinary," Györkös Žnidar said.

Asked about the 13 migrants turned back by Austria at Šentilj crossing on Wednesday as the new regime kicked in, she said they had re-entered Austria after repeated registration.

The minister repeated that Austria was still examining the lawfulness of the planned asylum seekers quota and said that Slovenia was not placing a limit on the number of migrants it takes for the time being.

Györkös Žnidar pledged for the authorities to do everything in their power to prevent Slovenia becoming a "buffer" for migrants, so there was no cause for concern.

But she reiterated that a priority was to halt the refugee wave on the Greek-Macedonian border, saying Slovenia had an interest for Macedonia to be helped to secure its border.

Slovenia has already deployed six police officers to Macedonia and sent border control equipment, and is willing to continue to help.

Slovenian police have registered 900 migrant arrivals today, and a total of 43,541 since the beginning of the year, data by 6 PM today shows.

Police data also shows that 1,148 migrants haven left Slovenia for Austria today, a total of 43,928 so far this year.