Violence erupting on the streets of Frankfurt comes after weeks of similar protests in French cities. ( Reuters: Kai Pfaffenbach )
A new flashpoint in the student-led protests that have swept Europe has emerged in the German city of Frankfurt.
The German government says stores were looted and at least 100 officers were injured over the course of the weekend.
Students marched in dozens of German cities demanding better education and lower living costs.
Looters and rioters have damaged stores and injured more than 100 police officers in the German city of Frankfurt, prompting ministers to warn of a crackdown.
The central German city emerged as the main flashpoint on Saturday after tens of thousands of people rallied in dozens of cities to demand better education and lower living costs in protests organised by campaign group "Gen Z regelt", which translates roughly to "Gen Z takes charge".
Hooded rioters damaged 17 stores, of which five were looted, Roman Poseck, interior minister of the state of Hesse, told a press conference on Sunday.
The protests across Germany were organised by campaign group Gen Z regelt, or "Gen Z takes charge". ( Reuters: Kai Pfaffenbach )
He said police deployed 1,300 officers, with more than 100 injured in clashes. Police arrested 54 people aged between 13 and 29.
"I am shocked by what I have seen, and there is no point in sugar-coating it. Let me make this very clear: Things cannot go on like this," Mr Poseck said.
Mr Poseck said most of those arrested were German nationals, adding that many of those involved in the disturbances were of an immigrant background, citing information from the police.
"Police currently estimate that they are dealing with between 1,000 and 1,500 violent troublemakers, predominantly from an immigrant background," he added.
Many protests across Germany were peaceful, with younger voters calling for government action to improve their lives. ( Reuters: Kai Pfaffenbach )
Frankfurt police reported violent disturbances including windows being smashed and petrol bombs, rocks and bottles being thrown at the emergency services.
German Interior Minister Alexander Dobrindt, a member of the conservative Christian Social Union, said perpetrators would be identified and held to account.
"I expect there to be severe penalties. We are not prepared to accept, in the slightest, that such incidents and such rioting should take place here," he told reporters on Sunday.
Police are vowing a harsher response to similar violence in the future. ( Reuters: Kai Pfaffenbach )
He accused "troublemakers from the immigrant community" of acting alongside left-wing extremists and other far-left groups, but did not provide evidence to support the claim or say which groups had joined the demonstrations.
Mr Dobrindt said a policing strategy based on a large security presence and deployments across multiple locations had proved effective.
In France, protests continued largely peacefully for a third weekend after extensive riots and looting on October 17 damaged shops, public buildings and businesses.
Mr Dobrindt said that border controls had been tightened ahead of the protests out of fear extremist groups from abroad could exploit them to stir riots.
