German officials said Thursday they had raided properties as part of a bribery probe into an MP, who is reportedly a far-right AfD lawmaker accused of spreading Russian propaganda.
The investigation targets Petr Bystron, the number two candidate for the Alternative for Germany party in next month's European Parliament elections, Der Spiegel news outlet reported.
Bystron last month denied media reports he was paid to spread pro-Russian views on a Moscow-financed news website, just one of several scandals that the extreme-right anti-immigration AfD is battling.
Police, and prosecutors in Munich, confirmed on Thursday they were conducting "a preliminary investigation against a member of the German Bundestag on the initial suspicion of bribery of elected officials and money laundering", without giving a name.
Properties in Berlin, the southern state of Bavaria and the Spanish island of Mallorca were searched and evidence seized, they said in a statement.
Bystron's offices in the German parliament, the Bundestag, were searched after lawmakers voted to waive the immunity usually granted to MPs, his party said.
About 70 police officers and 11 prosecutors were involved in the searches.
While acknowledging the probe was a "serious matter", the AfD's co-leaders Alice Weidel and Tino Chrupalla insisted that "no evidence" had been presented to back up the allegations.
In a statement on X, formerly Twitter, they urged a swift conclusion to the investigation so there was no suspicion that officials were "trying to influence the European election campaign".
But Health Minister Karl Lauterbach, a member of Chancellor Olaf Scholz's centre-left SPD party, said the case showed the AfD was a "great danger".
"While we defend our democracy against (Russian President Vladimir) Putin, these people betray us for money," he said.
The allegations against Bystron surfaced in March when the Czech government revealed it had broken up a Moscow-financed network that was using the Prague-based Voice of Europe news site to spread Russian propaganda across Europe.
Czech daily Denik N said some European politicians cooperating with the news site were paid from Russian funds, in some cases to fund their European Parliament election campaigns.
It singled out the AfD as being involved.
Denik N and Der Spiegel named Bystron and Maximilian Krah, the AfD's top candidate for the European elections and currently a serving MEP, as suspects in the case.
After the allegations emerged, Bystron said that he had "not accepted any money to advocate pro-Russian positions".
Krah has denied receiving money for being interviewed by the site.
On Wednesday the European Union agreed to impose a broadcast ban on the Voice of Europe, diplomats said.
The AfD's popularity surged last year, when it capitalised on discontent about rising immigration and a weak economy, but it has dropped back in the face of recent scandals.
On Tuesday, a court convicted Bjoern Hoecke, a leading AfD member and one of Germany's most controversial politicians, of deliberately using a banned Nazi slogan at a rally and fined him 13,000 euros ($14,000).
Last month, Krah's aide at the European Parliament was arrested on suspicion of spying for China.
In January, an investigation by media group Correctiv indicated AfD members had discussed the idea of mass deportations at a meeting with extremists, leading to a wave of protests across the country.