Viktor Orban said migrants entering Hungary in their thousands in the past weeks had “rebelled” against his police force, and order had to be restored.
Aid workers have been telling of “abysmal” conditions for refugees at a camp on the Hungarian-Serbian border.
Video footage has emerged of people being thrown bags of food at the camp in the town of Roszke.
Hungary has struggled to cope with some 150,000 migrants that have crossed its borders so far this year, en route from Greece to countries in northern and western Europe.
There have been tensions between the authorities and migrants, at border areas and key railway stations.
Hungary has insisted it is trying to fulfil its obligations as an EU member and register all new arrivals, but its attempts to control the flow – such as building a fence along its border with Serbia and staging border protection exercises – have proved controversial.
But, Mr Orban warned that from 15 September, tougher immigration laws would take effect and anyone crossing the border illegally could expect to be arrested.
He praised the police for doing a “remarkable” job “without force” in the face of unco-operative migrants who, he said, had “rebelled against Hungarian legal order”.
BBC correspondents and producers covering the migrant crisis on Twitter
- Anna Holligan at Roszke on the Hungarian border: “Unusual scenes… #refugees crossing in front of soldiers, suspect might not be the way next week #Hungary”
- Manveen Rana at Roszke: “A man held his baby out of the window shouting “oxygen, oxygen”. A guard shouted at him to get back in again”
- Bethany Bell in Nickelsdorf, Austria: “Austrian army putting up tents at the border”
- Wietske Burema at the Macedonia-Greek border: “Drilling a channel for a drinking water pipe for refugees at the border of Greece & Macedonia”
Elsewhere on Friday:
- The Czech Republic, Hungary, Poland and Slovakia again rejected the European Commission’s proposed mandatory quota system, sharing out 160,000 asylum seekers a year between 23 of the EU’s 28 members. Czech Foreign Minister Lubomir Zaoralek said countries “should keep control over the number” of refugees they could accept
- 432,761 people have entered Europe via Mediterranean routes, via Italy or Greece, so far this year, reports the International Organization for Migration, more than double the total for the whole of 2014
- Germany has put 4,000 troops on standby to help with the unprecedented influx of refugees, Defence Minister Ursula von der Leyen tells German media
- There is a bottleneck of more than 10,000 people at Hungary’s border with Austria. Existing shelters in the area are full and the army is putting up more tents. Some migrants have begun walking towards Vienna
- Hungarian camerawoman Petra Laszlo apologises for kicking migrants, saying “something snapped” in her when people broke through police cordons
A key point of tension in Hungary has been at a refugee reception centre in Roszke, where the authorities have been taking many migrants newly arrived from Serbia.
Scenes from inside the camp were revealed in video footage filmed by Michaela Spritzendorfer, the wife of an Austrian Green party politician who was delivering aid to the camp, and Klaus Kufner, a journalist and activist.
Ms Spritzendorfer said it was about 20:00, and police were throwing plastic bags containing food to around 100 people, including the elderly and the very young.
“These people have been on a terrible tour for three months,” she told the BBC.
“Most of them have been across the sea now and on the boat and through the forest and they’ve gone through terrible things and we, as Europe, we keep them there in camps like animals.”
At the scene: Anna Holligan, BBC News, Roszke
The Hungarian refugee camps have become humiliating holding zones for the thousands trying to cross the country’s borders. Journalists are banned from entering, but images shared by human rights groups and refugees are disturbing.
The Hungarian government has not yet commented, but the images will fuel the allegations that Hungary is failing to meet the minimum standards for the treatment of migrants, as laid out in the European Convention on Human Rights.
The Council of Europe has reminded member states that people should not be treated like prisoners.
Many of the people I’ve spoken to, from Raqqa, Idlib and Homs have become numb to violence in Syria, but their treatment in what is supposed to be a place of refuge is hard to bear.
Another aid worker, Irish volunteer Patrick Quirke, told the BBC that people were being kept in cages, guard dogs were running free and “from what I was told the food is very sparse, the conditions are cold, the children were cold and they weren’t being provided with any heating”.
Human Rights Watch said migrants were being kept in “abysmal” conditions at two detention centres in Roszke, lacking food and medical care. The group quoted two migrants who described the conditions as only fit for animals.
Hungarian police have said they will investigate the scenes from inside the camp.
A note on terminology: The BBC uses the term migrant to refer to all people on the move who have yet to complete the legal process of claiming asylum. This group includes people fleeing war-torn countries such as Syria, who are likely to be granted refugee status, as well as people who are seeking jobs and better lives, who governments are likely to rule are economic migrants.