Clashes at Germany's Heidenau asylum centre alarm government
German Chancellor Angela Merkel has strongly condemned violence at an asylum seekers' shelter that injured dozens of police officers.
Mrs Merkel described the behaviour at some in the eastern town of Heidenau as "abhorrent" and "shameful".
Security was increased at the newly-opened centre near Dresden at the weekend after two nights of protests.
Left-wing activists staging counter-demonstrations have clashed with the right-wing protesters.
Germany says it expects up to 800,000 people to seek asylum by the end of 2015.
German news magazine Der Spiegel reports that the violence on Friday night followed a demonstration earlier in the evening, called for by a Facebook group linked to the far-right NPD party.
The group later distanced itself from the violence that followed.
Germany shocked by riot - by BBC Berlin correspondent Jenny Hill
"The Nazi shame of Heidenau" is how Bild described what happened near Dresden. There was outrage too that the German chancellor did not immediately condemn the violence. "Merkel must break her silence," ran one headline.
And this morning she did. Her spokesman described the far-right demonstrations as "disgusting" and "shameful" - sentiments with which most Germans agree.
Attacks on asylum seeker accommodation are rising but the numbers are still relatively small. The neo-Nazis who hurled bottles and fireworks in Heidenau are a despised minority.
A recent poll revealed 67% of Germans were "very worried" by attacks on refugee homes. In another survey 93% said it was right to give asylum to those fleeing conflict. And an extraordinary number of people here are giving up their time or their possessions.
All over the country there are warehouses stacked with second-hand clothes, toys, supplies for the refugees.
Speaking ahead of talks with the French President Francois Hollande, Mrs Merkel said it was "abhorrent how right-wing extremists and neo-Nazis attempt to spread their idiotic message of hatred".
It was equally shameful, she added, that citizens, including families with children, "support these things by marching along".
In a statement President Hollande called for the creation of a "unified system for the right to asylum."
He added that Europe's migrant crisis was "an exceptional situation that will last for some time."
Police had to use tear gas and pepper spray in the early hours of Saturday morning to lift a blockade of the asylum seekers' shelter. Hundreds of people, some alcohol-fuelled, hurled bottles and stones at police, injuring 31 officers, reports say.
A further night of violence followed on Saturday, and two police officers were injured.
German media report that a police "control zone" introduced in the area immediately around the centre on Sunday appears to be working. The violence between left and right-wing groups on Sunday night took place outside this zone.
Vice Chancellor Sigmar Gabriel, visiting Heidenau on Monday, praised the town's mayor for his courage in speaking out against the violence.
Mr Gabriel was also due to speak to the refugees on Monday and tour the building where they are being lodged, which is in a former DIY store.
About 300 asylum seekers have already arrived at the reception centre, which is due to take 600 people.
Germany's Interior Minister Thomas de Maiziere has promised to use "the full force of the law" against those who carry out anti-refugee violence.