Austria’s highest court has annulled the result of the presidential election narrowly lost by the candidate of the far-right Freedom Party.
The party had challenged the result, saying that postal votes had been illegally and improperly handled.
The Freedom Party candidate, Norbert Hofer, lost the election to the former leader of the Greens, Alexander Van der Bellen, by just 30,863 votes or less than one percentage point.
The election will now be re-run.
Announcing the decision, Gerhard Holzinger, head of the Constitutional Court, said: “The challenge brought by Freedom Party leader Heinz-Christian Strache against the 22 May election… has been upheld.”
He added: “The decision I am announcing today has no winner and no loser, it has only one aim: to strengthen trust in the rule of law and democracy.”
Austria’s politics have been thrown into confusion. One of the most controversial and polarising presidential elections in recent history will have to be re-run.
This is a moral victory for the far-right, anti-immigrant and Eurosceptic Freedom Party, which launched the legal challenge last month after alleging “terrifying” irregularities.
The Freedom Party is hoping that the decision by the court will help its candidate Norbert Hofer win in the new election this autumn.
Mr Hofer said on Friday he was pleased that the court had taken “a difficult decision”, adding: “I have great trust in the rule of law.”
Mr Van der Bellen said he was “very confident” he would emerge the winner.
“Austria needs to be well represented in Europe and the world. If we can do it once, we can do it again,” he told reporters.
Austrian Chancellor Christian Kern said the court ruling showed that the country’s democracy was strong and he called for “a short campaign, a campaign without emotions”.
If elected, Mr Hofer would become the first far-right head of state of an EU country.
His party has based its election campaigns around concern over immigration and falling living standards for the less well-off.
After Britain voted to leave the EU, Mr Hofer said he favoured holding a similar referendum in Austria if the bloc failed to stop centralisation and carry out reforms “within a year”.
Last Sunday, he told the Oesterreich newspaper (in German): “If [the EU] evolves in the wrong direction, then in my opinion the time has come to ask the Austrians if they still want to be part of it.”