Ireland will not allow the Northern Ireland "backstop" clause in Britain's European Union withdrawal agreement to be dropped because doing so would be as big a threat to the country as Britain leaving without a deal, Prime Minister Leo Varadkar said on Saturday.
Leo Varadkar was responding to comments from some candidates seeking to replace Theresa May as prime minister.
Varadkar also rejected the notion of an expiry date on the backstop clause which would put the onus on the European Union rather than the United Kingdom to work out a workable solution for the island's unity. "But the only way to make sure that we convince our partners that we're determined to get that outcome is to prepare for no deal - and I think people do understand that".
Leading contenders in the race to become Britain's next prime minister have called for the controversial clause, created to avoid a border checks between Ireland and Northern Ireland, to be changed or scrapped.
The assumption is that no British government would agree to a separate status for Northern Ireland to the rest of the UK.
Speaking on Irish National Broadcaster RTÉ's Marian Finucane programme, the taoiseach said it was "alarming" some leading Conservatives were suggesting a no-deal Brexit.
He also responded to calls for a time limit to be attached to the backstop.
Varadkar again rejected a proposal for a time limit on the Northern Ireland clause, saying a backstop with a time limit is "not a backstop".
The backstop, which bedevilled Mrs May's deal, is an insurance policy created to avoid a hard border on the island of Ireland by keeping the United Kingdom in a customs union.
"What we expect, and I don't think it's unreasonable - we want to see that fleshed out, we want to see it exist, it demonstrated before we are willing to give up the backstop".
Boris Johnson has said the Irish backstop problems could be solved by having checks away from the border.
Asked how he would solve the border problem, he said: "Those problems are easily capable of solution, as I think the [European] Commission has said in the past, with maximum facilitation techniques and, after all, at the moment you already have goods conforming to different standards".