According to the new measures, Slovenian soldiers can assist police in patrolling the border, detaining people and handing them over to police, as well as issuing orders to civilians in the area.

The Slovenian government said it was "delusional" to expect small countries to succeed where larger ones had failed.

The country of two million has not excluded erecting a fence along its Croatian border.

Slovenia has already deployed 140 soldiers to the border to assist police, state secretary for interior affairs Bostjan Sefic told reporters.

Almost 20,000 migrants and refugees have arrived in Slovenia since Saturday, when Hungary sealed off its border with Croatia, forcing the people seeking refuge to take a detour towards Slovenia on their way to Austria and Germany.

Riot police on horseback led thousands of weary refugees marching across fields in Slovenia, as few buses are available to transport them to refugee camps.

Slovenia and Croatia also exchanged insults as Ljubjana complained that Zagreb is ignoring requests for advanced warnings on new arrivals of refugees. Croatia's interior minister Ranko Ostojic insisted that Slovenia was not accepting people quickly enough.

The wave of migrants and refugees has put a strain on the former Yugoslav republics in the region.

With at least 9,000 people landing on Europe's beaches every day, according to UN figures, the wave of migrants and refugees is not expected to decrease despite the approaching winter and the bitterly cold weather on the Balkan trail.

Slovenia's prime minister, Miro Cerar, said his country would also ask the EU for back-up police forces from other member states and additional equipment for its own officers.

Slovenian president Borut Pahor, meeting EU Council president Donald Tusk and EU Commission president Jean-Claude Juncker in Brussels on Tuesday, confirmed that Slovenia will also ask for financial help: "We need fast assistance of the European Union."

EU migration commissioner, Dimitris Avramopoulos, is expected to visit Slovenia on Thursday to discuss Ljubljana's requests.

In the meantime, thousands of people were stranded in the cold weather along the Croatian-Serbian border, as Croatian authorities struggled to transport people to its border with Slovenia.

News agencies report that at least 12,100 migrants are currently in Serbia, while some 6,000 migrants entered Austria from Slovenia on Tuesday.

EU dragging its feet

The EU's plan to relocate 160,000 people seeking asylum from frontline states Greece and Italy to other member states based on a quota system is lagging behind, according to sources.

Only 19 Eritrean asylum seekers have been relocated from Italy to Sweden so far, AFP reported, and only 6 member states out of the 23 required to do so have offered places for relocation.

Member states have also been slow to follow up with financial help, with only €474 million given out of the €2.8 billion pledged at an emergency EU summit in September.

In the meantime, Frontex, the EU's border agency, said member states had provided less than half of the 775 personnel it had requested to help in Greece and Italy.

Frontex said 291 guards would be deployed to both countries immediately.