Thousands of migrants kept streaming Monday into the Balkans, where tighter border controls caused bottlenecks, as the German government braced for an anniversary rally of the xenophobic PEGIDA movement, accusing it of spewing "hate and poison".
The unprecedented refugee wave into Europe has seen asylum seekers -- mostly fleeing war in Syria, Iraq and Afghanistan -- travelling via Turkey, Greece and through the western Balkans, hoping to seek safe haven in Germany and other EU states.
A new surge entered Macedonia from Greece at the weekend, with 10,000 crossing in just 24 hours, police said.
But tensions have built further along the migrant trail after Hungary shut its borders with razor wire, diverting the flow west to Slovenia, which in turn also limited arrivals.
On Monday Slovenia refused to let in more than 1,000 migrants arriving from Croatia, saying a daily quota had been reached.
The move stoked fears of a new human bottleneck, as a train carrying 1,800 people arrived overnight on the Croatian side of the border, but only 500 of the "most vulnerable", mostly women and children, were allowed to cross, police said.
Long lines also formed on the Serbia-Croatia border, where hundreds spent the night in rain and freezing temperatures.
The goal for many of the migrants has been the EU's biggest economy, Germany, which expects to take in around one million refugees this year, and where Chancellor Angela Merkel's open-door policy has sparked a dangerous backlash.
Two days after a man with a neo-Nazi background stabbed a pro-refugee politician in the neck, badly wounding her, Germany's anti-refugee PEGIDA movement was planning a mass rally to mark its first anniversary.
Police expect thousands to join the march of the "Patriotic Europeans Against the Islamisation of the Occident" in Dresden in the former communist East, as well as a large antifascist counter-protests, from 1600 GMT.
The movement had all but vanished after pictures surfaced in January showing its co-founder Lutz Bachmann sporting a Hitler moustache, but it has made a comeback since September, when Merkel opened the doors to a surge of asylum seekers.
Angry protesters have accused her of "treason" and last week carried a mock gallows with Merkel's name on it.
The chancellor on Monday again urged people to "stay away from those with hate in their hearts," her spokesman said.
Interior Minister Thomas de Maiziere said PEGIDA's organisers were "hardcore right-wing extremists" who "call asylum seekers criminals, and politicians traitors".
De Maiziere implored citizens, even if they are concerned about the record migrant influx, to "stay away from those who inject this hate, this poison into our country".
Anti-foreigner sentiment motivated a bloody attack in the western city of Cologne on Saturday when a man used a hunting knife to stab independent mayoral candidate Henriette Reker, 58, who is active in helping refugees.
Reker, who was seriously wounded in the neck, went on to win Sunday's election with an absolute majority.
The attacker, a 44-year-old unemployed man, had "a racist motivation" and said he had been active in a neo-Nazi group in the 1990s, according to police.
De Maiziere said the attack had left him "speechless" and also pointed to a tripling of attacks against asylum seekers and refugee homes from last year that had left more than 40 people injured.
Justice Minister Heiko Maas charged that "PEGIDA sows the hatred that breeds violence" and warned that "there are no excuses for those who follow gallows and Hitler beards".
The migrant influx has boosted support for populist right-wing parties in other European countries, including Austria.
A Swiss populist party known for its virulent campaigns against immigration, the EU and Islam won a record number of seats in parliamentary elections on Sunday.
In Germany, Merkel has faced a dip in opinion polls and a rebellion in her own conservative ranks, especially in the southern state of Bavaria, the main gateway for migrants.
While the Bavarian CSU party wants to establish "transit zones" along the Austrian border to hold and register asylum-seekers, a police union chief has called for a fence to secure the Alpine frontier.
A group of 188 of the 310 lawmakers in Merkel's conservative block has doubts about her open-border policy, and its chairman Christian von Stetten said considering "border fortifications" must "not be taboo", according to Bild daily.
Merkel, hoping for Turkey's help in slowing the migrant influx, held talks with President Recep Tayyip Erdogan in Istanbul.
The EU wants Turkey to tighten border security and house more refugees in return for billions in financial help, visa liberalisation for Turkish citizens and an acceleration of its stuttering drive for EU membership.
But Turkish Prime Minister Ahmet Davutoglu said on Monday said his country would not host migrants permanently to appease the European Union.
"We cannot accept an understanding like 'give us the money and they stay in Turkey'," he said in a television interview. "Turkey is not a concentration camp."