Some 4000 migrants have crossed into Croatia over the past 24 hours, the country's public broadcaster HRT has said.

Government data cited in the report suggests that, as of Thursday morning, more than 5650 people have found their way into Croatia since Hungary moved to close its border with Serbia. Another 4000 are expected in the next few days.

Buses carrying migrants from Presevo in Southern Serbia started traveling to the Croatian (instead of the Hungarian) border earlier this week after Budapest announced tough measures to protect its borders from the thousands willing to use them to reach the Schengen borderless area (of which Hungary is a member) and easily reach Germany from there.

Miro Cerar, Prime Minister of Slovenia (also a Schengen member) has warned his country is also introducing border controls.

Austia for its part is intending to beef up security at the border crossings with Slovenia after having adopted similar measures with regard to Hungary.

Separately, Hungarian Prime Minister Viktor Orb?n has told Die Welt newspaper that Budapest will have to comply with a decision to impose quotas if such is approved.

His comments came a day ahead of the Thursday vote in the EU Parliament on whether or not to relocate 120 000 asylum seekers from Greece, Italy, and Hungary.

MEPs' move will still have to be approved by EU Interior Ministers at their meeting scheduled for Tuesday. Some countries - like the rest of the Visegrad Group (which includes the Czech Republic, Slovakia, Hungary, and Poland) are voicing their opposition to the idea that quotas should be mandatory.

Late on Wednesday, clashes erupted between migrants and Hungarian riot police as the former were seeking to break through the Serbia-Hungary border.

At least 20 Hungarian police officers and two children were left injured. Twenty-nine people were detained during the unrest, one of them being labelled "terrorist" by police officers.

The Roszke-Horgos border in Hungary is now closed to traffic for at least 30 days, in an attempt to stem the flow of migrants.

On Wednesday evening, the Serbian Foreign Ministry issued a statement explaining it would sent "a note to Hungary calling on Hungarian organs to prevent a repeat of the situation that happened today when teargas canisters were fired into our territory," according to B92.

Meanwhile Serbian PM Aleksandar Vucic hurled criticism at some EU member states over their reaction to the increased migratory pressure.

Vucic said his country would tolerate no humiliation by other European states and called on the EU to react against members which deviate from core values.

Since the beginning of 2015, some 200 000 people have entered Serbia from neighboring Macedonia en route to Germany - currently at a pace of 2000 daily, B92 quotes Beta News Agency as saying.

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