A death threat was sent to Cologne Mayor Henriette Reker, police confirmed on Wednesday, June 19 just weeks after a German politician was murdered in what authorities believe was a "right-wing extremist" attack, Deutsche Welle reports.

Police in the western German city told the mass-circulation Bild newspaper that the threatening note is believed to have been sent by someone active in the right-wing extremist scene.

It is not yet clear whether the threats are connected to the shooting of Kassel regional president Walter Lübcke, who was killed in early June in what appeared to be an execution-style assassination.

While campaigning in 2015, Reker suffered serious injuries when she was stabbed by a right-wing extremist wielding a hunting knife. The attacker said he targeted Reker because of her pro-refugee stance.

The case is now being handled by investigators in Berlin, as several German politicians have also recently received death threats.

According to local public broadcaster WDR, one of the other politicians targeted was Andreas Hollstein, the mayor of the western town of Altena.

Like Reker, Hollstein was also stabbed, in 2017, by a man who shouted anti-migrant remarks before slashing the politician's neck with a knife in a kebab shop.

The recent killing of Lübcke, who was also known for his support of German Chancellor Angela Merkel's refugee policies, has raised fears about right-wing extremism in Germany. A suspect who is believed to be an extreme-right sympathizer is currently in custody over the killing.