Polish prosecutors have launched an investigation into far-right leader Grzegorz Braun after he declared the gas chambers at Auschwitz to be “fake” and said it is a “fact” that Jews have committed ritual slaughter of Christians. Denial of Nazi crimes is an offence in Poland that carries a jail sentence of up to three years.

Braun, who finished fourth in the recent presidential elections with 6.3% of the vote, made his remarks during an interview today with radio station WNET. The veteran far-right politician, who is a member of the European Parliament, has a long history of hateful and conspiratorial rhetoric regarding Jews and other minorities.

During the interview, Braun referred to what he claimed are the “lies of the Talmud, the Haggadah [two Jewish religious texts], and the Holocaust”. He said that Jewish organisations “condemn those who tell the truth that ritual murder is a fact and Auschwitz with its gas chambers is a lie”.

A longstanding antisemitic canard is that Jews murder Christians, in particular children, and use their blood for religious rituals. Meanwhile, many modern antisemites deny the fact that gas chambers were used at Auschwitz and other German-Nazi camps to murder Jews during the Holocaust.

After the interviewer contested Braun’s remarks, he reiterated them, saying that the Auschwitz Museum provides a “pseudo-historical account” about what happened at the camp and blocks research into the gas chambers. He also cited a book by an Israeli historian that he says proves Jews carried out ritual murder.

That led the interviewer to immediately cut short the broadcast, saying that there “are limits to political cynicism and sensationalism when it comes to several million victims and their memory”.

Subsequently, Anna-Maria Żukowska, head of the parliamentary caucus of The Left (Lewica), one of the groups that make up Poland’s ruling coalition, announced that she was filing a complaint to prosecutors regarding Braun’s remarks.

She accused him of violating article 55 of Poland’s law on the Institute of National Remembrance, which criminalises public denial of Nazi and communist crimes. Those found guilty can be punished by up to three years in prison.

Late on Thursday afternoon, the district prosecutor’s office in Warsaw announced that it had initiated an investigation into whether Braun had committed the offence of denying Nazi crimes.

Meanwhile, Piotr Cywiński, the director of the Auschwitz Museum, which is a Polish state institution, issued a statement condemning Braun’s “scandalous” comments, which he said were not only a violation of the law but also “an insult to the memory of the victims of the camp”.

“Grzegorz Braun’s words are not a ‘political provocation’, but a conscious lie and an act of ideological, antisemitic hatred,” said Cywiński. “They cannot remain without a decisive response from the state and all decent people – for whom the memory of Auschwitz is of particular importance.”

The museum director noted that, while it was primarily Jews who were victims of the gas chambers of Auschwitz, ethnic Poles, Soviet prisoners of war, and Roma were also murdered in them.

At least 1.3 million prisoners were transported to Auschwitz during the war, with at least 1.1 million of them killed at the camp. Around one million of those victims were Jews, most of whom were murdered in gas chambers immediately after their arrival. The second largest group of victims were ethnic Poles.

Cywiński said that the museum would itself file a notification to prosecutors regarding Braun’s remarks. He also appealed to Polish media to stop giving space to Braun, who “has repeatedly shown that he cannot function in the public space without vandalism, lies, hate speech and racism”.

Last week, Braun was presented by prosecutors with seven sets of charges relating to four incidents, including his attack on a Jewish religious celebration in parliament two years ago.

He is also being investigated over a series of incidents during the recent presidential election campaign, including when he vandalised an LGBT+ exhibition, made antisemitic remarks during a televised debate, and removed a Ukrainian flag from a public building.