A record number of right-wing protesters stormed through the eastern German city of Dresden for the latest in a series of anti-Islam demonstrations that have alarmed the country's politicians.
Police estimated that some 17,500 people attended Monday's rally, staged by the group calling itself Patriotic Europeans against the Islamisation of the West, or Pegida. This week, the protest was billed as a carol-singing gathering in front of the Semperoper opera house.
Those numbers would make it the biggest gathering since Pegida's weekly protests started in October.
An estimated 4,500 people demonstrated in Dresden against Pegida in a counter-demonstration, while some 12,000 also protested against it in Munich.
Pegida's organisers insist they are protesting only against extremism and not against immigrants or Islam itself.
But the demonstrations have received support from far-right groups, prompting concerns that anti-foreigner sentiment is on the rise.
Last week, German chancellor Angela Merkel called for citizens not to be taken in by the far right.
"There's freedom of assembly in Germany, but there's no place for incitement and lies about people who come to us from other countries," she told reporters in Berlin last week. "Everyone (who attends) needs to be careful that they're not taken advantage of by the people who organise such events."
Opposition parties have accused Merkel's conservative Union bloc of being too timid in its criticism of the protests up to now, suggesting that she fears losing voters to the far right.
Jürgen Todenhöfer, a German reporter who was the first Western journalist to be embedded with Islamic State fighters, said that his experience in Iraq and Syria had made him realise how counter-productive such protests are.
"No one should play down the possibility of terrorist threats in Germany," he wrote in a Facebook post after his return this week.
"But you should not exaggerate them also. After all, a German has never been killed in Germany by Islamists. But many German Muslims have been killed by German right-wing radicals.
"Groups such as Pegida are providing the facts upside-down. They are doing IS's work for them, they have a great interest in an escalation of conflict between Muslims and non-Muslims in Germany. IS confirmed me this to me several times."
Immigration has emerged as a contentious topic again in Germany, partly due to the recent sharp rise in asylum applications, particularly from Syrians.
More than 150,000 people sought refuge in Germany during the first 11 months of the year, an increase of 40,000 compared with 2013.
Last week, fires broke out at three empty buildings earmarked to house asylum seekers, and anti-foreigner slogans and swastikas were painted at one site in Vorra, near Nuremberg. Police said they were treating the fires as arson.