RB Leipzig coach Marco Rose has slammed Cologne fans for singing songs against eastern Germany during their 5-1 home defeat on Friday.
Chants of "we hate eastern Germany" rang out in Cologne as Leipzig moved up to fourth in the table temporarily and Cologne remained marooned in the relegation play-off spot.
The states which used to make up the communist East Germany before the fall of the Berlin Wall in 1989 and German reunification a year later are still poorer than western Germany, although Leipzig is now a booming city.
"People who don't know what it is like should come over and see," Rose, who was born in Leipzig during the communist era, told reporters.
"There are a lot of cool people there. Just like here (in Cologne). There are a few idiots. Just like here. So in the end, everything is actually very, very similar. That's why we tore down the wall at some point, including in people's minds."
Cologne's managing director Christian Keller strongly criticized his own fans.
"We had an anti-discrimination matchday today. All the more reason to wonder what's going on in some people's heads," he said. "Such chants are not acceptable. It's only a minority. But it's a shame that this minority exists."
