Switzerland's highest court has ordered the re-running of a 2016 referendum after ruling that voters were informed in an erroneous and incomplete way with the information that they were given before being asked to make their decision.

The poll asked the country's voters whether married couples and co-habiting partners should pay the same tax, and was rejected by a margin of 50.8 percent to 49.2 percent.

Two years after the referendum took place, the government revised its estimate of the number of couples who were being penalized by the existing system from 80,000 to 454,000.

As a result, Switzerland's Federal Court has ruled, the "incomplete detail and lack of transparency in the information provided by the Federal Council violates the freedom of vote of citizens.

"Given the tight outcome of the poll and the seriousness of irregularities, it is possible that the result of the voting could have been different."

It is not clear what will happen next, but the country's Federal Council said "it will draw the consequences to determine as soon as possible the continuation of operations."

Switzerland's direct democracy system allows an issue to be the subject of a referendum if it gathers 100,000 signatures.

A similar system has been adopted recently in the British Parliament, where issues are debated if a petition secures the same number.

The recently established petition calling on Prime Minister Theresa May to revoke Article 50, the legislation that set in motion the country's withdrawal from the European Union, was signed by more than six million people.

The challenge to the Swiss tax referendum came from the Christian Democratic Party, based on the inaccuracy of the statistics supplied by the government.

The party said it welcomed the verdict of the court, calling it a "boost for the political rights of Swiss voters."

Opponents, however, said the ruling could potentially undermine the country's political system as it could encourage time-wasting and frivolous challenges to the outcomes of other public votes.

All kinds of topics have come up for the popular vote in Switzerland over the years, including healthcare funding, immigration, transport policy and the minimum wage.

In 2013, after the country's biggest bank UBS AG received state aid during the financial crisis, almost 70 percent of voters supported a proposal which gave company shareholders a binding annual vote on executive pay.

And in 2016, a highly contentious measure to expel foreigners convicted of crimes failed after being rejected by 59 percent of voters.