The ruling is a blow for the far-right Alternative for Germany (AfD) party ahead of regional and European elections.
The right-wing populist Alternative for Germany party lost a case in which it appealed against its classification as a suspected right-wing extremist party.
The Office for the Protection of the Constitution (BfV) has considered the AfD to be a suspected right-wing extremist organisation since 2021.
In some federal states in eastern Germany, it has even been categorised as a "definitely" right-wing extremist.
At the federal level, the party has appealed against being labelled a suspected right-wing extremist organisation.
In 2022, the Administrative Court of Cologne ruled in favour of BfV, finding sufficient evidence of anti-constitutional tendencies within the AfD. This judgment has now been upheld by a court in Münster.
The court found that there was a sufficient legal basis for the designation, while stressing that the step doesn't inevitably lead to the party being designated a proven case of right-wing extremism.
The AfD is grappling with multiple scandals, including a trial against member Bjorn Hoecke for deliberately using a Nazi slogan at a rally, and accusations of links to China after one of its members Maximillian Krah had his assistant arrested on suspicion of spying for China.