Taoiseach Leo Varadkar has said it is "disappointing but not entirely surprising" that the UK white paper will not be published in time for the EU summit at the end of this month.
It comes as British Prime Minister Theresa May has said the UK government's white paper on its Brexit position will not be published until after the summit.
The Taoiseach said given it is that two years since the Brexit referendum and less than nine months until the UK is due to leave the EU, it is a "real problem" that Britain has not outlined how it sees it new relationship with the bloc.
However he said he did not believe this would create problems for the October deadline, and that rather than things stalling after the June summit, he said he believed negotiations would have to intensify.
Mr Varadkar also said that Michel Barnier’s comments that it would not be feasible to apply the Northern Ireland 'backstop' to all of the UK, "makes sense".
He added: "If we can resolve some or all the issues in relation to border issues that relate to Ireland with a UK-wide solution it is something I'm enthusiastic about".
With British ministers aiming to complete the negotiations by October, many had expected the document to be released ahead of the European Council meeting in Brussels.
Speaking in Canada, Mrs May said her Cabinet would hold another meeting at her country residence, Chequers, to finalise the details.
Mrs May said she is is keen to show she is making progress on the process of leaving the European Union after criticism from her Foreign Secretary Boris Johnson and a row with Brexit Secretary David Davis in recent days.
Plans for the Brexit white paper were announced in May when Mr Davis said it would be the British government's "most significant publication on the EU since the referendum".
Mrs May told reporters at the G7 summit in Canada: "There is going to be a lot of activity in the negotiations over the coming weeks."
The return of the EU (Withdrawal) Bill to the Commons next week will be followed by the 28 June European Council.
Mrs May said that at the gathering of EU leaders "we'll be talking about finalising withdrawal agreement but also pressing on the future relationship".
"After that I'll be bringing my ministers together for an away day at Chequers to finalise the white paper that we are going to be publishing and then before Parliament breaks for the summer we'll be bringing the Trade and Customs Bills back to the House of Commons and throughout all of that time the negotiations will be continuing.
"The British people want us to deliver Brexit and I'm getting on and doing exactly that and I'm doing it because there is a prize for us at the end of this which is a brighter future for Britain in control of our laws, our money and our borders."
Mrs May's announcement on the white paper comes after she was forced to defend her approach after criticism from Mr Johnson.
She said the Foreign Secretary has strong views on Brexit "but so do I", as she attempted to downplay Mr Johnson's outburst on how negotiations are progressing.
She claimed "nobody ever said it was going to be easy" to quit the European Union but pledged to "deliver Brexit for the British people".
Mr Johnson's indiscreet remarks about Brexit, which saw him call for "guts" in the negotiations, emerged as Mrs May was in mid-air en route to Canada.
Britian's Foreign Secretary told a private dinner there was a risk Brexit "will not be the one we want" and would keep the UK locked in orbit around the EU.
He also claimed fears about the border on the island of Ireland were out of proportion and said it was "beyond belief that we're allowing the tail to wag the dog in this way".
It comes as the PM's latest Brexit proposals received a frosty reception in Brussels, Michel Barnier raising objections to her plan for a time-limited customs backstop covering the whole UK.
But within minutes of concluding a press conference in Brussels, the chief EU negotiator took to Twitter to correct the impression that he was rejecting the UK proposals out of hand, stressing that they would be the subject of discussions in the coming days and weeks.
To avoid any confusion between the EU backstop & the UK customs paper: I reiterate that our backstop cannot apply to whole UK. 4 freedoms are indivisible. This is not a rejection of the UK customs paper on which discussions continue. #Brexit— Michel Barnier (@MichelBarnier) June 8, 2018
Responding, Mrs May told the BBC: "This is a negotiation, Michel Barnier has said exactly that point.
"We have put a proposal on the table, on this backstop relating to Northern Ireland, we will now sit down and negotiate it with the European Union."