The Taoiseach has warned the new UK Prime Minister that he will have to row back on some of the things he has said in recent days if he truly wants to secure a Brexit deal.

Leo Varadkar was speaking after Boris Johnson said there would be no Brexit deal without the ‘abolition’ of the Irish border backstop.

The two leaders have yet to speak since Mr Johnson was confirmed to office on Wednesday.

Speaking in Donegal this evening, Mr Varadkar again warned that the backstop is an essential part of any deal.

“If he means what he says by wanting to leave with a deal and wanting to have a free trade deal with the EU, well then he will have to depart from some of what he said in the last couple of days,” he said.

The Taoiseach Leo Varadkar at the MacGill Summer School in Glenties, Donegal, 26-07-2019. Image: Michael McHugh/PA Wire/PA Images

The EU has repeatedly ruled out any renegotiation of the Brexit Withdrawal Agreement, which includes the backstop.

Yesterday, the Chief EU Negotiator Michel Barnier said Mr Johnson’s demand for the abolition of the backstop was “of course unacceptable.”

He said the EU remained willing to rework the political declaration on the future relationship to alleviate fears of the backstop ever coming into force.

“There isn’t going to be a deal without a backstop,” said Mr Varadkar.

“As the EU, we have made that abundantly clear all along. The backstop is an integral part of the withdrawal agreement.

“Without the backstop - which gives us the guarantees that we need - not only is there no withdrawal agreement, there is no transition phase or implementation phase for the UK and there can be no discussions on a free trade agreement.”

Prime Minister Boris Johnson arriving at the West Midlands Police Learning and Development Centre, Birmingham, 26-07-2019. Image: Jacob King/PA Wire/PA Imagesnson

Speaking in London this evening however, Mr Johnson again suggested the border issue could be resolved in negotiations after the UK leaves the bloc.

“I want to say to our Irish friends, what I have said repeatedly,” he said.

“Under no circumstances will the UK be instituting any kind of checks at the frontier in Northern Ireland.

“Of course not; we don’t want that. But the UK will be coming out of the EU on October 31st and after we come out, of course there will be all sorts of discussions to be had with our Irish friends about how to ensure that we have continued frictionless trade – which is what we want.”

The Taoiseach Leo Varadkar at the MacGill Summer School in Glenties, Donegal, 26-07-2019. Image: Michael McHugh/PA Wire/PA Images

This evening, the new Northern Secretary Julian Smith left the door open to the possibility of a deal that includes the backstop.

Mr Varadkar said he will find out exactly what Mr Johnson’s red lines are when the pair meet in person.

“He has demonstrated a degree I think of flexibility I think in the past, voting both for and against the withdrawal agreement,” he said.

“I don’t think he is going to entirely inflexible in the future.

“But dealing with counterparts, you really only get a proper sense of where they are going and what their real red lines are if you like in the tête-à-tête – in that kind of one-to-one meeting.”

Mr Johnson rejected claims that his actions since entering 10 Downing Street have all been aimed at an upcoming general election.

He also insisted that there will be no second Brexit Referendum.

“The British people voted in 2015, in 2016, in 2017,” he said.

“What they want us to do is to deliver on their mandate to come out of the EU on October 31st.

“They don’t want another electoral event. They don’t want a referendum; they don’t want a general election – they want us to deliver on that mandate.”

“We are going to deliver on the mandate of the British people which is to take the UK out of the EU whole and entire on October 31st.”

This afternoon, the Tánaiste Simon warned that Mr Johnson's stance had put Britain on a “collision course” with the EU and Ireland.

Mr Johnson has spoken to the European Commission President Jean-Claude Juncker and the French President Emmanuel Macron by phone in recent days.

He is due to travel to France to meet President Macron in person in the coming weeks.