Delays are likely at ports following a no-deal Brexit, the Taoiseach has said.
Ireland is involved in sensitive discussions with its European partners about what happens if the UK crashes out of the bloc.
Mr Varadkar said the Republic is ready for the withdrawal, with 700 extra officials employed and temporary structures at Dublin Airport and Dublin and Rosslare sea ports.
I cannot see there not being delays. This is a big change
He told RTE Radio 1’s Today With Sean O’Rourke show: “I cannot see there not being delays. This is a big change.
“Will there be delays at Dover and Calais? Absolutely.
“Will there be potential delays at Dublin and Rosslare? Yes. I think it will be the same, but it will work.”
The EU has given the UK an Article 50 extension until the end of October.
Mr Varadkar said if there was no transitional agreement then customs and tariffs declarations could be made online and checks conducted at business level.
The Republic is proposing that the island of Ireland be treated as a single unit for the purpose of checks at ports.
The Taoiseach said the country’s next budget would focus on the challenges posed by Brexit.
Taoiseach wants early meeting with new British PM
The Taoiseach said he is looking forward to meeting with the new British Prime Minister and hearing how they plan to secure a withdrawal agreement.
The next leader of the Conservative Party is due to be announced on July 23, either Boris Johnson or Jeremy Hunt, with Theresa May expected to hand in her official resignation the following day.
Leo Varadkar said "there are options" for the new PM when it comes to Brexit.
He said: “The UK could still stay in the European Union...they could stay in the Single Market using the Norway model.
"The backstop could apply for Northern Ireland and not the UK to get away from the European plot to tie the UK into the orbit of Europe."
Mr Varadkar said what matters is the avoiding a hard border between Northern Ireland and the south.
"I am willing to compromise if there is no hard border, there is a guarantee for the rights of Northern Ireland citizens, the preservation of North-South cooperation and the protection of the economy and the Good Friday Agreement.
"We will talk to see if they have any suggestions.”
Tune in now to @TodaySOR where I’m talking to Sean about #brexit and the economy pic.twitter.com/G3Pj0kC9bW
— Leo Varadkar (@LeoVaradkar) July 18, 2019
There is a possibility of the UK parliament taking control of the agreement, the Conservatives have a majority of only three, that’s including the DUP and quite a few Conservatives would do anything to prevent a no-deal.
“Circumstances can change, we have to hear from the UK Prime Minister before we set dates for action. We have yet to hear from the Prime Minister what they have in mind.
“The withdrawal agreement is not something that was imposed on the UK.”
Asked about the ‘big reveal’ of Brexit plans, he said: “it will be when we know ourselves, we will have to give businesses decent notice.
“If there is no deal then tariffs will have to be imposed, that can be done electronically. Checks are being done at ports already.
“We’re proposing that Ireland – north and south – be treated as a unit.
“The Budget coming up will have to be different because of two major issues – Brexit and climate."