Martin Sellner, the co-founder of the Identitarian Movement of Austria (IBOe), came under investigation together with some of his associates when it emerged that in 2018 he had received a donation of 1,500 euros ($1,800) from Brenton Tarrant.
White supremacist Tarrant killed 51 Muslim worshippers in attacks on two mosques in the city of Christchurch in March 2019.
Sellner admitted to having had contact with Tarrant on several occasions and prosecutors looked into whether charges could be brought against him or those close to him for “participation in a terrorist organisation”.
But the spokesman for the prosecutors' department in the city of Graz, Hansjoerg Bacher, confirmed to AFP that the investigation had been “dropped”.
Sellner's house was also searched as part of the investigation, but a court ruled in 2019 that the raid was illegal.
Sellner told AFP on Friday that investigations targeting his wife and the IBOe as an organisation had also been dropped last month.
Austrian media report that another investigation against Sellner for suspected fraud is however ongoing. The IBOe has been described by Austrian intelligence services as “agents of modern right-wing extremism”.
Sellner and the Identitarians are proponents of the far-right “Great Replacement” conspiracy theory according to which white Europeans are being deliberately supplanted by non-white immigrants.
Tarrant's manifesto was also titled “The Great Replacement”.
The Identitarians are also known for anti-immigrant stunts such as a 2017 incident in which members gained access to the roof of the Turkish embassy in Vienna, unfurling a banner addressing Turkish President Recep Tayyip Erdogan and reading: “Erdogan, take your Turks home.”