Thousands of demonstrators clashed with police in Germany's capital Berlin as the protesters tried to block a far-right march from going ahead.
Around 2,000 people blocked the planned route of a demonstration organised by the far-right National Democratic Party (NDP) on Saturday and threw stones, bottles and fireworks at troops, injuring several police, the AP news agency reported.
The 100 activists had planned to march through Berlin's Kreuzberg district, which is home to a large immigrant population, but were only able to proceed just a few hundred metres before their path was blocked.
Police spokesman Thomas Neuendorf told AP: "We ran into a lot of disruptions staged by the counter-protesters.
"We witnessed stones and bottles thrown at police, pyrotechnics were employed and things were set on fire."
He added: "Numerous policemen were injured and arrests were made for trespassing, resistance against state authorities and attempts to aid jailbreak."
Authorities said four NPD supporters and nine counter-demonstrators had been arrested by mid-afternoon on Saturday.
The NDP is reported to have links to neo-Nazi groups, and according to Germany's security services, the nationalist party has a racist, xenophobic and anti-Semitic agenda.
In December, all 16 German states filed a motion in the federal constitutional court to ban the party, arguing that it incites racism and aims to overthrow the democratic government.
The group is alleged to have murdered nine immigrants between 2000 and 2006, bombed a barbershop owned by an immigrant in Cologne in 2004, and murdered a policewoman in 2006.
In 2012, the far-right Pro Deutschland group staged an anti-Muslim protest outside a mosque in Berlin.
The protesters carried the controversial caricature of Prophet Mohammed which originally appeared in the Danish newspaper Jyllands-Posten in 2005, along with slogans reading "Hasta la vista Salafista" or "Goodbye Salafism".
The demonstration was condemned by local Muslim groups, including the German Islamic Council, which said such far-right protests "threaten the social and religious peace in Germany".