Germany has placed the far-right AfD party under surveillance for posing a threat to democracy, local media has reported.
The move is seen as a blow to the anti-immigration party in a big election year.
The Federal Office for the Protection of the Constitution (BfV) has classified the Alternative for Germany as “suspected” of having ties to right-wing extremism, Der Spiegel magazine said.
The decision, reportedly made late last week, will allow intelligence agents to shadow the party, tap its communications and possibly use undercover informants.
It follows a two-year investigation and a report containing over 1,000 pages of evidence, including several hundred speeches and statements by AfD members at all party levels, Der Spiegel said.
The anti-Islam, hard-right AfD has often courted controversy by calling for Germany to stop atoning for its World War II crimes.
Founded in 2013 in opposition to eurozone bailouts for Greece, the AfD has grown and shifted further right over the last seven years, shedding several leaders along the way.