The Alternative for Germany (AfD) has filed a lawsuit against ex-party chief Frauke Petry in a branding dispute, the Bild newspaper reported.

"The AfD sued me in Munich to cancel the trademark I had registered for The Blue Party," Petry told Bild.

A Munich court spokesperson confirmed the lawsuit.

Petry left the AfD after its success in the September 2017 election, accusing the party of being too extremist.

In October, she submitted a trademark for The Blue Party, and in January it was registered at Munich's patent office.

AfD spokesman Christian Lueth told Bild that the party sued Petry to prevent her from benefiting from the AfD's reputation.

"Our logo and similar markings or colors are protected. We want to prevent imitators or political freeloaders from raising their profiles on our name and fooling the public," he said.

cw/sms (dpa,Bild)