Austria's interior minister said Saturday he was "ashamed" after the country's highest court declared the result of May's presidential election null and void because of widespread procedural "sloppiness".

Friday's ruling by the Constitutional Court invalidating the outcome of the May 22 election means that Norbert Hofer of the Freedom Party (FPOe) will have another shot at becoming the EU's first far-right president.

I am "disappointed, ashamed.... The fact that this sloppiness and breaking of the law took place has shaken me massively," Wolfgang Sobotka told Oe1 public radio, adding that he felt "embarrassed".

The court's ruling, triggered by an FPOe legal challenge, found that postal votes in 14 areas -- or 78,000 votes -- were opened too early or by unauthorised persons, and so could in theory have been tampered with.

Since this represented more than double the independent ecologist Alexander Van der Bellen's winning margin of just 31,000 votes, the court said that the election must be held again. No date has been set, but it is expected to be in September.

Newspapers on Saturday were outraged. The Oesterreich tabloid called Austria a "banana republic -- probably the only country outside Africa and Kazakhstan that is unable to count votes properly".

"It's amazing that in a Western democracy an election has to be repeated," said voter Hermann, 36, as he waited for a bus in Vienna. "The whole thing is stupid," agreed pensioner Josef, 80.

For the re-run, Sobotka said that media outlets and research institutes would not be provided with partial results before voting officially ends -- a practice that dates back decades.

"There will be no results before all votes, including postal votes, have been counted," he said.

Possible legal changes under discussion include allowing postal votes to be counted on the day of the election, and not the day after as now, Sobotka said.

The Kurier daily reported that Sobotka wants to have election observers from the Organization for Security and Co-operation in Europe (OSCE) present for the next round.

- Brexit impact -

Traditionally the president's job has been largely ceremonial but Hofer has indicated that he will make use of hitherto untapped powers afforded under Austria's constitution.

Winning the Hofburg palace would also be of enormous symbolic importance for the FPOe two years before the next scheduled general elections, and be a fillip to other populist parties Europe-wide.

Experts say it is impossible to predict the outcome, although some say that they expect lower turnout, which could boost Hofer, 45, portrayed as the friendly face of the anti-immigration FPOe.

Britain's June 23 decision to leave the EU could make a possible Austrian exit an election issue, with Hofer pledging a referendum if the EU fails to reform, becomes more centralised or if Turkey joins.

"The British case has shown that the EU, this EU, is clearly too remote from people. So I am convinced that a renewal of the EU is needed so that it returns to its basic values and to being closer to the people," Hofer told Italian daily Corriere della Sera.

"A change in EU treaties towards a further reduction in member states' national responsibilities would automatically lead to a referendum in Austria," the paper quoted him as saying.

The slightly dishevelled economics professor Van der Bellen, 72, is staunchly pro-EU.

With polls showing Austrians largely in favour of remaining in the bloc he could turn Hofer's comments to his advantage, particularly if Britain is seen to be suffering from its decision, commentators say.

"Who knows what will be happening in Britain in September. Brexit won but there haven't exactly been big celebrations," political expert David Pfarrhofer from polling firm Market told AFP.

Source: AFP