The Taoiseach has said that in the event of a no-deal Brexit the UK would have to accept full regulatory and customs alignment in Northern Ireland if it were to honour its obligations under the Good Friday Agreement.
Speaking in Davos, Leo Varadkar also said that the UK could struggle to negotiate free trade deals elsewhere around the world if the Irish border question remained unresolved.
He said: "The United Kingdom would have a responsibility to abide by WTO rules and both the UK and Ireland would have responsibilities to honour the Good Friday Agreement and the peace process.
"So I think we would end up in a situation where EU and Ireland and the UK would have to come together, and in order to honour our commitment to the people of Ireland that there be no hard border, we would have to agree on full alignment on customs and regulations, so after a period of chaos we would perhaps end up where we are now, with a very similar deal.
"The United Kingdom in a no-deal scenario will face enormous difficulties.
"In a no-deal scenario Ireland will still be in the single market, and will still be part of all those trade deals which come with being part of Europe, the trade deal with Japan, the trade deal with Canada, the trade deal with Korea, the trade deal with Singapore.
"In a no-deal scenario, the UK won't have any trade deals with anyone, and I think it will be very difficult for them to conclude any trade deals with the question of the Irish border unresolved. Given we have a solution on the table already, let's ratify that."
Separately, the Taoiseach and European Commission President Jean-Claude Juncker spoke by phone this evening, according to a Government spokesman.
The spokesman said: "President Juncker once again emphasised full solidarity with Ireland.
"They looked forward to continued close cooperation between Ireland and the European Commission, including on intensifying 'no deal' contingency action in the coming weeks."