Irish Prime Minister Leo Varadkar | Jack Taylor/Getty Images Leo Varadkar: Brexit was ‘not fully thought through’ Irish prime minister says he has to ‘stand firm’ on the backstop issue.

Brexit is an "act of self-harm" that has not been "fully thought through," said Irish Prime Minister Leo Varadkar.

Speaking to Euronews on Thursday on the fringes of the World Economic Forum in Davos, Switzerland, Varadkar said he would defend Ireland's interests by standing firm on the controversial Northern Ireland backstop mechanism, designed to avoid a hard border on the island of Ireland.

"I often hear people, particularly people who support Brexit in the United Kingdom, say that they don’t want a hard border but they also don’t want a backstop, but what are they offering in return?" he said.

Brexiteers, he said, had offered a promise to solve the border issue over two years or with technology "that doesn't yet exist."

Varadkar's blunt comments will do little to curry favor with Brexiteers in the British Cabinet and on the Tory backbenches, who see him as intransigent on the backstop issue — which they suspect the EU has used for negotiating gain. But the Irish PM was adamant that he needs a guarantee of no hard border in the future.

"There is no way that I, as prime minister of Ireland, looking out for our citizens, looking out for the best interest of our economy, looking out for the peace process, I could exchange what is a legally binding workable guarantee agreed by 28 governments ... for a promise," he said. "That’s why I have to stand firm on this.”

“I believe they're honest in their intent, but as it’s been the case with Brexit really from day one, I’m not sure it’s been fully thought through," he added.

Asked about comments earlier this week from Polish Foreign Minister Jacek Czaputowicz suggesting that a time-limited backstop could solve the issue, Varadkar said he would discuss this with Polish Prime Minister Mateusz Morawiecki later on Thursday.

"I think that probably was an attempt to be helpful," he said, "an attempt to put forward a solution but in doing so in many ways exposed and highlighted the reasons why a time-limited backstop would be so difficult for us to accept."

The Irish PM added that, "Brexit is a problem that was created by Britain, and I think it’s a real act of self-harm."