Tens of thousands of people rallied in the southwestern city of Stuttgart yesterday to protest against a contentious rail project, a day after riot police clashed with demonstrators.

Chants of “Shame on You!” and a cacophony of vuvuzelas rang out from the crowd which organisers put at more than 100,000 people, hours after Chancellor Angela Merkel had appealed for calm.

The night before police used water cannons, tear gas and batons to disperse 20,000 protesters, leaving hundreds of people needing medical treatment.

“Many people are traumatised, because yesterday... was a catastrophe, we weren’t expecting such violence from the police,” said Stuttgart native Werner Braetschkus.

Local police spokesman Stefan Keilbach said yesterday’s demonstration had so far passed off without injuries. Police had yet to release a crowd estimate for the protest.

“I would hope that demonstrations like these would pass off peacefully,” Mrs Merkel told public broadcaster SWR. “This must always be tried, and anything that leads to violence must be avoided.”

Following the clashes with police on Thursday more than 400 people including minors needed medical treatment, mostly because of the tear gas and pepper spray but also for broken noses and wrists as well as cuts, organisers said.

A blast from a water canon knocked an eye out of one protester, both organisers and police said.