Austrian far right leader Norbert Hofer has been granted a re-run of May's presidential election which he lost by 30,000 votes over fears concerning absentee ballots.

Hofer, the candidate of the Freedom Party, was ahead when the polls closed on May 22. However, his opponent Alexander Van der Bellen won when absentee ballots were counted.

However, Austria's Constitutional Court decided that rules in handling the absentee ballots had been breached, bringing the result into question.

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Austrian far right candidate Norbert Hofer, pictured right, expected to be voted president in May's election

The Freedom Party candidate, centre, was leading the poll until some 200,000 postal ballots were counted

Hofer complained the postal ballots had not been handled correctly and nullified May's election result

Once the absentee ballots were counted, Van Der Bellen was ahead by 30,000, with 50.3 per cent compared with 49.7 for Hofer.

The Freedom Party complained following the vote claiming the law had been contravened in one way or another in most of the 117 electoral districts, including the sorting of absentee ballots before electoral commission officials arrived and related violations of the rules.

The rerun is expected to be held in September or October.

Court president Gerhart Holzinger said: 'The challenge brought by Freedom Party leader Heinz-Christian Strache against the May 22 election... has been upheld.'

Gun enthusiast Hofer, 45, came top in a first round in April but then lost in a runoff with the 72-year-old Van der Bellen, sparking relief among Europe's centrist parties.

Hofer, right, was defeated by Green candidate Alexander der Bellen, left, in May's presidential election

The role of Austrian president is mostly ceremonial, but the far right Freedom Party are planning a major push at the next scheduled general election in 2018 and are even considering an EU exit referendum

Preliminary results had given Hofer a narrow lead but after some 700,000 postal votes were counted, the Greens-backed Van der Bellen was declared the winner of the largely ceremonial post the next day.

The FPOe, which is topping opinion polls ahead of the next scheduled general election in 2018 tapping rising unease about immigration, launched a legal challenge on June 8 claiming massive irregularities.

These included allegations that tens of thousands of votes were opened earlier than allowed under election rules and that some votes were counted by people not authorised to do so.

As the court heard from dozens of witnesses, Van der Bellen's lawyer had described the transgressions as having an 'insignificant' impact on the election result, but in vain.

Friday's ruling stops in its tracks Van der Bellen's planned inauguration on July 8. It is unclear when a new election will be held.

In the meantime, current President Heinz Fischer will still step down as planned and will be replaced on an interim basis by three parliamentary officials - one of whom is Hofer.

The decision sets in motion what is likely to be a hard-fought and nail-biting new summer election battle between van der Bellen and Hofer.

It remains to be seen whether the FPOe's success in getting the election held again will translate into getting Hofer into the Habsburg dynasty's former imperial palace, the Hofburg.

It is possible that Britain's referendum decision on June 23 to become the first member of the European Union to leave the bloc could also turn Austria's future membership into a key election issue.

Hofer, echoing French National Front leader Marine Le Pen, said after the Brexit bombshell that he would be in favour of holding a referendum in Austria if EU fails to implement necessary reforms 'within a year'.