Serbia's police say they have caught 71 migrants and arrested two people smugglers who transported them in vans. Serbian officials have vowed to step up military and police patrols on the borders with Bulgaria and Macedonia to stem the continuing influx of migrants. The Balkan route, used by nearly 1 million migrants last year to cross to mainland Europe, was closed in March. [...] hundreds still try to enter illegally daily in an attempt to reach the EU. Migrants are seeking alternative routes to the European Union after a crackdown on crossings to the Greek islands started in March, as part of an agreement between the EU and Turkey to stop the flow of migrants and refugees to Europe.