Ansons has applied to a Hamburg court to stop Asos using the brand in the country to stop potential customer confusion.
The retailer claims that “oral and written similarities” between the two brand names risks the “dilution of the longstanding Anson’s brand.”
If the court rules in favour of the German retailer, Asos could be forced to rebrand and trade under a different brand in Germany, hampering its global growth strategy.
A spokesperson for Asos says the German menswear business is being “opportunistic” and says there is “zero evidence” of any consumer confusion over the two brands.
Asos says it will fight the claims and is “confident of its position” in Germany.
Asos launched its German site in October last year and reported last week that its international business overtook its UK business for the first time in quarter four.
Last year Asos was prevented from using the German website Asos.de as part of its pre-launch marketing and from hosting a German-language pop-up banner on its UK website promoting the launch of the German site.
A hearing is due to take place on 3 May.
Asos is also facing a dispute in Switzerland by cycling clothes specialist Assos.