BERLIN (AP) — Germany's domestic intelligence agency has put the Alternative for Germany party under observation due to suspicions of extreme-right sympathies, German media reported Wednesday, a move against the biggest opposition party in parliament that comes only six months before a national election.

Alternative for Germany, or AfD, has been fighting in court against such measures, arguing that the publicity surrounding such a move so close to Sept. 26 election would damage the party's electoral chances.

Once the news was reported by the German news agency dpa, Der Spiegel, ARD public television and other media, AfD co-chairman Tino Chrupalla accused the Federal Office for the Protection of the Constitution, known by the initials BfV, of intentionally leaking the information in an attempt to influence public opinion about the party.

The BfV's behavior is “scandalous,” he told dpa.

Interior Ministry spokesman Steve Alter would neither confirm nor deny the reports and would not comment due to "ongoing proceedings.” The BfV also refused comment.

AfD parliamentary leaders Alexander Gauland and Alice Weidel said being put under observation was “completely unjustified and has no basis.”

“It is no coincidence that this information was was leaked to the press in the year of a federal election and only a few days before two important state elections,” they wrote in a statement. “A targeted attempt is being made here to reduce the AfD's chances with the help of the domestic intelligence agency.”

AfD entered Germany's national parliament as the third-biggest party in the 2017 election, benefiting from a backlash at the time against the influx of more than 1 million asylum-seekers. It is currently the largest of four opposition parties in the national parliament and has lawmakers in all 16 state assemblies.

The party has moved steadily to the right since it was founded in 2013 for critics of the shared euro currency. Several senior figures have quit in recent years, warning that the party was being taken over by far-right extremists.

Recent polls have shown support for AfD, which won 12.6% of the vote in 2017, at between 9% and 11%.

The new move to put the party as a whole under observation came more than two years after the BfV announced it was examining public comments by party members and its links to extremist groups more closely.

In January 2019, the agency put the the youth wing of the party, as well as a party faction linked to a prominent leader in eastern Germany, Bjoern Hoecke, under covert surveillance over extremism allegations.

At the time, the BfV cited the youth organization’s stated goal of creating an ethnically pure country and efforts by Hoecke’s faction — known as “The Wing” — to downplay Germany’s Nazi past.

The Wing — now officially dissolved, although its representatives remain in the party — also suggested it might pursue “revolutionary” means to achieve its political aims, warranting scrutiny from the BfV.

Germany's Central Council of Jews applauded the move to classify the entire party as a “suspected case” of extremism and put it under surveillance.

The moves “confirm the danger posed by the AfD,” said its president, Josef Schuster. “It tried to create a respectable façade, but that couldn't hide its radicalism.”