Officials in Germany's eastern state of Saxony sought to avert further unrest in the city of Chemnitz before the far right gathers for another anti-immigration protest later on Thursday after several violent confrontations this week.
Thousands of people took part in two days of protests against asylum seekers in Chemnitz this week after police arrested a Syrian and an Iraqi on suspicion of fatally stabbing a German man on Sunday.
Germany is deeply divided over Chancellor Angela Merkel's 2015 decision to take in more than one million migrants, many of whom fled conflicts in Syria, Iraq and Afghanistan.
"We will see to it that those who have committed this homicidal crime are condemned, and swiftly," Michael Kretschmer, Saxony's premier told reporters in Chemnitz.
"We will see to it that those who ran through the city with Hitler salutes are also convicted," he said.
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The authorities said federal police and police from other states including Hessen and Bavaria would be drafted in to support local forces during the far right protest at Chemnitz's football stadium later on Thursday.
Kretschmer plans to meet with local residents to discuss immigration inside the stadium at around the same time, he said.
Chemnitz lies Germany's formerly Communist east which has become the heartland of anti-immigrant groups including PEGIDA and the Alternative for Germany (AfD) political party which won 13 percent of the vote in a 2017 federal election, its strongest showing yet.
In Wismar, another eastern town, police called for witnesses to come forward over an attack late on Wednesday on a 20-year-old migrant who was beaten with an iron chain by three assailants.
At around noon in a rainy and cold Chemnitz on Thursday there was still no sign of the extra police which the local authorities said would be present at the protest due to start at 6 p.m. local time (1700 GMT).
The Chemnitz stabbing has raised concerns of possible links between police and the far right in Saxony after prosecutors in the northern city of Bremen opened an investigation into a lawmaker, a former police officer, who is accused of leaking information of the arrest warrant against the Iraqi suspect.
Chemnitz mayor Barbara Ludwig vowed to clean up her city's image, telling reporters: "This city is something completely different to what you had to see and what has been shown in the media in the past few days.
The AfD and PEGIDA, which are under observation by intelligence agencies, say they will march again in Chemnitz on Saturday to "mourn Daniel H. (the stabbing victim) and the others killed by Germany's forced multiculturalization."