Germany's spy agency on Friday classified the far-right Alternative for Germany (AfD) as "extremist", enabling it to step up monitoring of the country's biggest opposition party, which decried the move as a "blow against democracy".

Germany's domestic intelligence service on Friday designated the AfD as a right-wing extremist group, handing authorities greater powers to monitor the party and fuelling calls for it to be banned. The classification gives authorities greater powers to monitor the party by lowering the barriers for such steps as intercepting telephone calls and using undercover agents.