A prank video in which a heterophobic taxi driver rants against straight couples has gone viral ahead of Ireland's gay marriage referendum.

In the YouTube video, produced by British taxi app company Hailo, an Irish cab driver treats unsuspecting passengers in Dublin to his heterophobic views telling one customer: "We don't normally take heteros in the car," and another, "You always said Cain and Abel -- it wasn't Jane and Abel, you know?"

The video is part of Hailo's 'Drive for Equality' campaign, in which the company is offering free trips to Irish people to their local polling station for the referendum.

The Irish public will vote for or against same-sex marriage in a referendum on 22 May. Current polls predict the vote will be in favour of the change, making Ireland the first country in the world to approve same-sex marriage off the back of a popular vote.