The leak of an arrest warrant which names one of the chief suspects in a stabbing that set off neo-Nazi riots in Germany this week has raised fears that the country’s police may have been infiltrated by the far-Right.

The confidential document, which was shared by far-Right groups on social media, names a 22-year-old Iraqi, one of two immigrants being held on suspicion of stabbing a German-Cuban man to death in the eastern city of Chemnitz at the weekend.

The killing set off the most serious neo-Nazi violence in Germany for several years. More than 6,000 far-Right protestors roamed through the streets of Chemnitz on Monday night, attacking foreigners, giving the Hitler salute and chanting: “A dead foreigner for every dead German”.

Police confirmed on Wednesday that the leaked document was genuine and said they had opened an investigation into suspected “violation of official secrets”.

The leak has added to growing concerns that far-Right sympathisers may have infiltrated the local force in the east German state of Saxony, where Chemnitz lies.

There are fears of possible vigilante attacks after the leaked document gave the full name and address of one of the arrested men. Other migrants at the shelter where he was living spoke of their fear the building could be targeted.