Germany's domestic intelligence service on Friday designated the far-right AfD party as an extremist group, handing authorities greater powers to monitor it and fuelling calls for it to be banned.

The anti-immigration Alternative for Germany (AfD) slammed the move as a "heavy blow" to democracy, just months after they won second place in national polls, and vowed to mount a legal challenge.

The BfV domestic intelligence agency, which had already designated several local AfD branches as right-wing extremist groups, said it decided to give the entire party the label due to its attempts to "undermine the free, democratic" order in Germany.

It cited in particular the "xenophobic, anti-minority, Islamophobic and anti-Muslim statements made by leading party officials".

The classification gives authorities greater powers to monitor the party by lowering the barriers for such steps as intercepting telephone calls and deploying undercover agents.

The decision drew swift condemnation from the conservative US administration. US Secretary of State Marco Rubio called the move "tyranny in disguise" and said "Germany should reverse........

© International Business Times