New documents suggest that the German police knew more about the threat posed by Tunisian terrorist Anis Amri than claimed, according to reports.

On December 19th 2016 Amri murdered a Polish haulier and stole his vehicle, which he later drove into a bustling Christmas market in the German capital.

The Tunisian, who used multiple identities as he gamed the system in Germany, had already had his asylum application rejected and had even been subject to a deportation order before he committed his attack.

Amri had also been linked to radical Islam and multiple crimes – but the police ended their undercover surveillance of him in September 2016, claiming they had not found evidence of a threat.

However, the Irish Times reports that Berlin broadcaster RBB has seen documents suggesting the local State Criminal Police Office (Landeskriminalamt, or LKA) had recognised the increasing threat to public safety Amri posed before making this decision.

The newspaper cites an August 2016 report which describes Amri as posing a “growing violent threat” – after authorities had already reduced observation to monitoring the Tunisian’s mobile phone.

Hans-Christian Ströbele, a politician representing Germany’s opposition Green Party, said he was “now convinced the attack could have been prevented. We need a full parliamentary inquiry into the Amri case.”

Berlin state interior minister Andreas Geisel reportedly claimed not to be aware of the new documents, but confessed that they raised questions about the version of events police presented. Local politicians have demanded a full federal investigation, to determine whether the police have been dishonest about their failings prior to the attack.

This news emerges just days after Bild Am Sonntag reported that North Rhine-Westphalia interior minister Ralf Jäger was informed that “Amri poses a threat in the sense of a terrorist attack” by authorities, but personally intervened to prevent his deportation.

Jäger has also been accused of being a key figure in the attempt to cover up mass sexual assaults by migrant men in Cologne on New Year’s Eve in 2015.