Thousands of refugees arriving in Hungary have been taken to closely guarded camps surrounded by chain link fencing, barbed wire and patrolled with police dogs.
Hungarian police said on Thursday that 3,300 refugees were taken to camps on Wednesday for initial processing after crossing the Serbian-Hungarian border.
The AP news agency reported that refugees will later be moved to asylum-seeker centres in other parts of the country.
Basic data is collected at the camps, although in some cases police also take fingerprints.
This is separate from the fingerprinting done by the immigration authorities, which happens at a later stage, typically in the asylum-seeker centres.
The temporary holding facilities are closed and refugees and migrants cannot leave them.
The detention of refugees came as Budapest prepared to deploy its military to bolster its border and stop people from crossing. Al Jazeera has learned that the military is undergoing an exercise to prepare for the deployment.
On Thursday, another 3,000 migrants crossed into Austria at the main border point with Hungary, but thousands remain in Hungary, while a record 5,000 more have arrived at the Serbian border with Hungary, according to reports from several news agencies and local media.
Al Jazeera's Mohammed Jamjoom, reporting from the border town of Roszke in Hungary on Thursday, said there is fear and confusion after authorities started to round up the refugees.
"There's so much fear among the refugees, and they are completely uncertain about what will happen in the days to come."
Heavy rain on Thursday worsened the already "terrible condition" of refugees stuck at the border, he said.
"It's very cold and the refugees are freezing. Although there are medics and volunteers trying to help, they are simply not enough," he said.
"They just want a little comfort and compassion."
Place of humiliation
Human Rights Watch said Hungary has become a place of humiliation for Syrian refugees.
"They are blocked here, they are suffering in the heat, we see children all over the place collapsed in absolute exhaustion," said Peter Bouckaert, Human Rights Watch's emergencies director.
"Hungary cannot cope with this influx of asylum seekers, they're not properly treating these people, and they either have to meet their international obligations and their obligations towards the EU or they have to let these people go to where they want to go, which certainly is not Hungary."
Hungarian police, however, rejecting allegations that they mistreat the refugees.
Spokeswoman Viktoria Csiszer-Kovacs said refugees at police-run points near the border with Serbia and at registration centers are being given provisions and medical attention.
She called allegations of abuse "blatant lies", saying "illegal migrants are being looked after regularly and constantly".
On Thursday, Austrian rail company OeBB said that train services between Austria and Hungary would be suspended at least for the rest of the day because Austria cannot handle the volume of migrants crossing its borders.
"It would be irresponsible to simply let people keep streaming in and spend the night at train stations," the spokesman said.
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Meanwhile in Germany, Chancellor Angela Merkel has visited a home for refugees in Berlin, saying she hopes that the integration of newcomers will be helped by their children learning German in school.
Merkel's brief visit on Thursday to a refugee home in the suburb of Spandau, came as Germany contemplates the task of absorbing the influx of refugees from Syria and elsewhere.
Merkel told reporters after her closed-doors visit that she spoke with two refugee families, one of them with two children now attending a kindergarten.
"Their integration will certainly take place in part via the children, who will learn German very quickly in kindergarten. And I hope and believe that the great majority will want to learn our language very quickly."
Later on Thursday, Barack Obama, the US president, directed his administration to prepare to take in at least 10,000 Syrian refugees next year, according to a White House spokesman.
The number reflects a "significant scaling up" of the US commitment to accept refugees from the war-torn country, Josh Earnest, the White House press secretary said.
Source: Al Jazeera