Hungarian troops overnight began laying a razor-wire barrier along its border with Croatia to keep migrants out, Prime Minister Viktor Orban says, following a similar move along the frontier with Serbia.
"During the night work already began on building the technical border closure.... It seems we can rely on help from no one," Orban said in an interview on Friday (local time) on public radio after thousands of migrants entered Croatia seeking to travel to northern Europe.
"Forces are being redeployed, 600 soldiers are already at the scene, 500 will arrive there in the course of the day, at the weekend another 700. Two hundred police are there already, another 100 will go down today and another 500 at the weekend," he said.
"There will be no sandhill or molehill to hide behind, we will defend our borders."
He said the barrier was being put in place along 41 kilometres of the 330-kilometre border. Along the rest flows the difficult-to-cross Drava river.
Hungary this week sealed its border with Serbia, cutting off a major entry point into the European Union for tens of thousands of migrants from the Middle East, Asia and Africa travelling up through the western Balkans.
This has diverted about 13,000 migrants from Serbia into Croatia, overwhelming local authorities and forcing Zagreb to close most of its border on Thursday.
Local media reported small groups of migrants crossing into Hungary from Croatia on Thursday.
Police said on Friday that 453 illegal immigrants were detained in Baranya county next to the Croatian border by midnight, mostly Syrians and Afghans.
Hungary meanwhile declared a "state of crisis" in two counties near the Croatian border and in two others near the Slovenian and Austrian borders.
A similar state – paving the way for the large-scale deployment of the army and police in border control, pending parliamentary approval – is already in force in two other counties along the Serbian border.
"The western Balkans route is still there. The fact the Hungarian-Serbian border is now closed has not stopped the flow," Orban said.
In addition to laying razor wire all along the border with Serbia, Hungary is also building a fence four metres high and also intends to reinforce its border with Romania.