The Australian Government has called the Labor party “villains” for threats to block a costly and time-consuming public vote on same-sex marriage.

Labor leader Bill Shorten has called a plebiscite, as proposed by Prime Minister Malcolm Turnbull, the “second-best option”.

The Labor party and the Greens have criticised the idea of a plebiscite, saying it is costly and time-consuming, and that the matter should be settled with a parliamentary vote.

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On Sunday Government frontbencher Christopher Pyne told Sky News: “Bill Shorten and the Labor Party are … putting at risk the possibility of marriage equality in Australia. They are the villains in the piece.

“Mr Shorten cannot guarantee that there will be a vote in the Parliament on marriage equality. So he’s quite prepared to say to all those same-sex couples who want to marry … he’s quite prepared to tell them ‘no’, we’re not going to allow that to happen.

“So the the only villain in the piece here is Bill Shorten, not the Coalition.”

Speaking on Sunday in Melbourne, Shorten said: “We want to have marriage equality and we want to do it as quickly as possible.

“A vote in the parliament is the quickest, cheapest, least divisive mechanism.”

A plebiscite, or public vote, has been criticised as a stalling technique, and for costing taxpayers in Australia estimates of hundreds of millions of dollars.

In addition, the public vote would be non-binding, and would have to be followed by a parliamentary vote in order to make same-sex marriage law.

This is despite a majority of parliamentarians in Australia having indicated that they are pro-same-sex marriage.

But Prime Minister Malcolm Turnbull has hit back, suggesting that the plebiscite would be the quickest way to legalise same-sex marriage.

He told ABC TV: “There is no question that the fastest way, the way to guarantee that there is a vote in the parliament on gay marriage in this parliament, is to support the plebiscite.”

The Australian Green Party has already indicated that it will oppose the plebiscite but has admitted being unable to block it without Labor’s input.

But Turnbull remains adamant that Labor will allow the vote to go ahead, and that arguing against the plebiscite in case the no-vote wins is “the most anti-democratic argument.”

“The Labor Party must want to delay same-sex marriage for a very long time if they are briefing that,” he added.

Turnbull has broken an election pledge he made to hold a public vote om same-sex marriage by the end of the year, announcing that it will take place in 2017.

The Prime Minister said that he could not just hold a parliamentary vote on equal marriage because “he is not a dictator” – so a public vote is being held.

Labour have criticised the move calling it expensive and pointless. The vote is estimated to cost $160 million of taxpayers money, or as much as half a billion dollars, according to estimates by PricewaterhouseCoopers.

The liberal party remains divided on equality issues and Turnbull himself has been a vague supporter of equal marriage.

He previously came under fire for removing LGBT content from a sex education campaign.