BERLIN (AP) — Germany's domestic intelligence agency says it is formally placing parts of the far-right Alternative for Germany party under surveillance after classifying it as extremist.

Thomas Haldenwang, head of Germany's BfV intelligence agency, said Thursday that a radical faction within the AfD known as “The Wing” is considered a proven extremist organization.

The Wing is led by AfD's regional chiefs in the eastern states of Thuringia, Bjoern Hoecke, and Brandenburg, Andreas Kalbitz.

Hoecke is well known for his far-right positions, and notoriously called Berlin’s memorial to the victims of the Nazi Holocaust a “monument of shame.”

Haldenwang described Hoecke and Kalbitz as "right-wing extremists," noting Hoecke's anti-Islam and anti-immigrant rhetoric and close ties to other known extremists.

"This is a warning to all enemies of democracy," he said, citing Germany's grim Nazi past as a warning.

“We stand together and act.”

The party immediately criticized the move.

Putting The Wing under surveillance increases pressure on the party and could strengthen calls for it to be banned. Civil servants who are members of The Wing could face scrutiny and even disciplinary measures.