BERLIN (AP) — German authorities are formally placing parts of the far-right Alternative for Germany party under surveillance after classifying it as extremist, the country's domestic intelligence agency said Thursday.

Thomas Haldenwang, head of the BfV intelligence agency, said that after more than a year of examination his office has concluded that a radical faction within Alternative for Germany, known as “The Wing,” meets the definition of a “right-wing extremist movement."

"This is a warning to all enemies of democracy," said Haldenwang, noting that it was his agency's duty to prevent growing far-right extremism from overthrowing the country's democratic order the way the Nazis did in the 1930s.

Alternative for Germany immediately criticized the move, which allows authorities to use covert methods to observe The Wing and its estimated 7,000 supporters. They make up about 20% of the party's overall membership but hold significant sway over its direction, according to former party members including its one-time leader Frauke Petry.

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

Haldenwang described Hoecke and Kalbitz as "right-wing extremists," noting Hoecke's historical revisionism, his anti-Islam and anti-immigrant rhetoric and his close ties to other known extremists outside of the party. Hoecke has described Berlin’s memorial to the victims of the Nazi Holocaust a “monument of shame” and called for a "180-degree turn" in the way Germany remembers its Nazi past.

“We mustn't just keep an eye on violent extremists but also watch those who use words to spark fires,” said Haldenwang, adding that anti-Semitism, hatred of Islam and racism spread online or in political arenas provides the “breeding ground” for violence.

Germany has been shaken by a series of far-right killings over the past year, including the slaying of a regional politician from Chancellor Angela Merkel's party, the attack on a synagogue in Halle and a deadly mass shooting targeting people with migrant backgrounds in Hanau.

“Right-wing extremism and terrorism are currently the biggest threats to democracy in Germany,” Haldenwang told reporters, adding that more than 200 people have been killed by right-wing extremists in the country since 1990.

Kalbitz, the AfD leader in Brandenburg, called the intelligence agency's decision “factually unfounded and completely politically motivated.”

Putting The Wing under increased surveillance could strengthen calls for it to be banned. Germany's top court rejected a bid to outlaw the far-right NPD party in 2017, deeming it too insignificant in part because it had no presence in parliament. Alternative for Germany, by contrast, has seats in all 16 state assemblies and the federal parliament.

Intelligence scrutiny of the The Wing could also have consequences for any supporters who are civil servants or state employees. “They will get into trouble” with their superiors in the future because the AfD faction's aims run counter to the German Constitution they swore to uphold, Haldenwang said.