Irish Taoiseach Leo Varadkar urged the Government to be “more specific” about relations once the UK is no longer a member of the European Union, following a meeting with Prime Minister Theresa May.
Mr Varadkar stressed Mrs May’s decision to rule out a hard border between the Republic and Northern Ireland was “very important” but demanded detail on future relations.
He said: “I have always encouraged the British Government to be more specific about how they see the future relationship between Britain and Ireland and between the United Kingdom and the European Union.”
Mr Varadkar also said divorce talks with Brussels have so far made insufficient progress to allow starting negotiations on a post-Brexit trade deal.
But he claimed there was still time to resolve the issue before the 27 remaining EU countries make a decision on the matter next month.
He said: “I don’t think, at this stage, it would be possible to say that sufficient progress has yet been made, but it may well be possible by the end of October when we meet in Brussels.”
Mr Varadkar stated the decision to progress the talks would be shaped by the views of EU’s chief negotiator Michel Barnier.
The Irish Taoiseach said: “Certainly, we will be very much guided by the report that Michel Barnier will make to the prime ministers and also the report that the European Parliament will make.”
Mr Vadakar is the first EU leader to visit Mrs May since her landmark speech in Florence last week.
During her address, Mrs May proposed a post-Brexit transitional period after the UK formally leaves the EU in March 2019.
She set out plans for an implementation period which “the existing structure of EU rules and regulations” would apply – and people from the EU would continue to be able to “live and work” in the UK under a registration scheme.
Mr Varadkar described the proposal as a “step in the right direction”. He also praised her assertion that there should be “no physical infrastructure” on the Irish border after Brexit.
The Government is working on a “practical solution” to deal with the border issue, Downing Street said.
A Number 10 spokesman said: “The Prime Minister made clear how the UK will be the strongest friend and partner to the EU after we leave the EU and how maintaining the reciprocal arrangements for the Common Travel Area and the citizenship rights guaranteed by the Belfast Agreement were at the heart of our approach.
“On the border between Northern Ireland and Ireland, the Prime Minister reaffirmed how we will not accept any physical infrastructure at the border and how we are working on delivering a practical solution that allows for the most seamless possible movement of goods between the UK and EU.
“The Prime Minister thanked the Taoiseach for his welcome of her Florence speech and they discussed the period of implementation which would enable people and businesses, both in the UK and in the EU, to adjust to the new arrangements in a smooth and orderly way.”
Mr Varadkar and Mrs May also discussed options for breaking the political deadlock over powersharing in Northern Ireland.