Prime Minister Orešović recently discussed the refugee issue with German Chancellor Merkel.
Police officers from tourist destinations have been sent to border areas.
Some question whether the caretaker Prime Minister should represent Croatia at important international events.
The migrants were detained at the railway station in Slavonski Brod.
Slovenia fears a possible new migrant wave.
An NGO is worried what will happen with the refugees.
Croatian rules for asylum-seekers could hardly be more restrictive.
First several migrants arrive in Croatia from Italy, according to the European plan for migration management.
The border crossing was closed for a few hours on Wednesday night.
Another protest against Slovenian border fence held in Croatia and Slovenia.