BERLIN (AP) — German intelligence officials have placed a regional branch of the far-right Alternative for Germany party under observation, a move that comes as its leading figure fights his expulsion from the party for failing to disclose his ties to extremist groups.

Officials in Brandenburg, an eastern region that surrounds Berlin, said Monday the local branch of the domestic intelligence agency decided to step up scrutiny of the party. The state’s top security official, Michael Stuebgen, said the party has become increasingly radical there and is now “dominated by aspirations that are very clearly directed against our free democratic order.”

Federal authorities already have formally placed a radical faction within Alternative for Germany, known as “The Wing,” under surveillance after concluding that it meets the definition of a “right-wing extremist movement.”

Alternative for Germany’s leader in Brandenburg in recent years, Andreas Kalbitz, was a key figure in The Wing — which was officially disbanded earlier this year. Last month, a majority of the party’s national leadership voted to expel him. Kalbitz has vowed to take legal action against the decision.

Kalbitz has a long history of involvement in groups that promote a revisionist interpretation of Germany’s war-time history and was photographed in 2007 at an event hosted by the HDJ, a neo-Nazi youth movement that has since been banned.

Much of Alternative for Germany’s branch in Brandenburg is standing behind Kalbitz, and he remains a member of the party’s caucus in the regional parliament.

Alternative for Germany came third in Germany’s 2017 national election but has recently lost ground in opinion polls. It is strong in eastern regions such as Brandenburg, where it is the second-biggest party in the state parliament.

Alexander Gauland, a leading member of Alternative for Germany who was Kalbitz’s predecessor as its leader in Brandenburg, said the intelligence agency’s decision was wrong.