British Prime Minister Theresa May has said there would be no physical infrastructure imposed on the Irish border after the UK leaves the European Union.
Addressing the House of Commons on the latest European Council summit, Mrs May also said that the Brexit talks were within touching distance of securing a deal on citizen's rights.
She told MPs that efforts were continuing to preserve the common travel area between Ireland and Britain.
She said: "We’ve also made significant progress on Northern Ireland, where it is absolutely imperative that joint work on the peace process is not affected in anyway.
"The Belfast agreement must be at the heart of our approach, and we have clearly agreed that the unique circumstances across the whole of the island of Ireland will require specific solutions.
"There will not be any physical infrastructure at the border, and we’ve also developed joint principles to ensure the continuation of the common travel area."
Mrs May was also urged to listen to British businesses and rule out a no deal option over Brexit.
It comes after British businesses stressed the need for a transition deal to be agreed as quickly as possible.
A draft letter intended for Brexit Secretary David Davis showed that five of Britain's biggest business lobby groups stressed the need for an early deal on post-March 2019 arrangements, warning that firms are preparing to make "serious decisions" with consequences for jobs and investment early next year.
Former Tory minister Anna Soubry referenced the letter from business representatives which she said warned of the "consequences of no deal and relying on World Trade Organisation rules".
After Mrs May's speech in the House of Commons, Ms Soubry said: "They said the Government should give certainty to business by immediately ruling this option out under any circumstances.
"Will the Prime Minister agree to listen to British businesses and would she even go so far today as finally to rule out no deal."
However, Mrs May said the British government had been "engaging with" and "listening to" business, adding: "I was very clear that the implementation period was something that business was very keen on having and ensuring that they had that smooth and orderly process of withdrawal.
"But we are in a negotiation with the EU 27 and I think it is important to remember as part of that negotiation that if we want to get a good deal for the United Kingdom, I think the best way to get a bad deal for the UK is to say that we will accept anything that they give us, regardless.
"We have to be clear that what we are working for is a good deal but I am optimistic about that because we have made some progress and I believe that the good deal that we're seeking is in the interest of both sides."
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Earlier, Britain’s Foreign Secretary Boris Johnson urged European leaders to press ahead with Brexit negotiations.
He said "now is the time to get on with it" after last week's European Council summit agreed to the 27 remaining EU members beginning internal preparations for the next phase of talks, which will cover trading arrangements and a possible transitional phase.
He said that if both sides "think very creatively and very positively" then a deal can benefit people and businesses on both sides of the English Channel.
Mrs May has requested a time-limited transition of around two years with the UK and EU trading on broadly similar terms to now and payments to Brussels to fulfil already agreed budget commitments.
But although EU leaders have agreed to begin scoping work on a future relationship, they have made clear to Mrs May she must make more concessions on a divorce payment to unlock talks on trade and a transition.
The private letter, which is believed not to have been sent yet, was reportedly signed by the Confederation of British Industry, British Chambers of Commerce, manufacturing trade body EEF, the Institute of Directors and the Federation of Small Businesses.
It said: "Agreement (on a transition) is needed as soon as possible, as companies are preparing to make serious decisions at the start of 2018, which will have consequences for jobs and investment in the UK.
"And the details of any transitional arrangement matter: the economic relationship the UK and EU has during this time-limited period must match as close as possible the status quo.
"It is vital that companies only have to undertake one adjustment as a result of the UK's withdrawal, not two - and that businesses, the UK Government and authorities in the EU have enough time to make the changes needed to deliver Brexit successfully."
Juncker aide accuses May's ex-policy chief of 'false' claims
Meanwhile, a senior aide to European Commission President Jean-Claude Juncker has hit back after being accused of leaking sensitive details of a dinner between Theresa May and the European Commission chief.
Mrs May's former chief of staff, Nick Timothy, blamed Martin Selmayr for an account of the private meeting published by German newspaper Frankfurter Allgemeine Zeitung.
But Mr Selmayr, Mr Juncker's chief of staff, accused Mr Timothy of spreading "false" claims and insisted that Brussels did not want to weaken the prime minister's position.
In his response to Mr Timothy, he suggested there were some people who had an interest in undermining the "constructive" relationship between Mr Juncker and Mrs May.
In the highly personal account of last Monday's dinner, Mrs May was said to have "begged for help", and seemed "anxious" and "tormented" as well as "despondent and discouraged", according to FAZ.
After the dinner, a joint statement was released agreeing to accelerate Brexit talks.
And later in the week, at the European Council summit, EU leaders said they would begin scoping work on future trade talks while making clear to Mrs May that she must make more concessions on Britain's divorce payment for negotiations to progress.
Earlier this year, Mr Selmayr was accused of leaking to the same newspaper details of a private dinner between Mrs May and Mr Juncker at 10 Downing Street, which the Commission president was said to have left "10 times more sceptical" than when he arrived.
Mr Timothy, who worked for Mrs May at the time of the previous leak, said the new disclosure showed there are figures in Brussels who want Britain to leave the EU with either no deal or on terms that would punish the country for Brexit.
But Mr Selmayr has denied being behind the leak or that Mr Juncker ever made the comments about Mrs May's emotional state.
He also dismissed the suggestion the EU was being "punitive" and claimed it was an attempt to frame the EU side of the negotiations and "undermine talks".
Firms not bluffing when they threaten to shift away from London - mayor
Companies are not bluffing when they threaten to move business from London due to uncertainty over Britain's departure from the European Union, mayor Sadiq Khan said today.
The mayor added that a transition deal would allow them to make plans more securely.
Mr Khan was responding to Goldman Sachs CEO Lloyd Blankfein's tweet that he would spend more time in Frankfurt due to Brexit.
Just left Frankfurt. Great meetings, great weather, really enjoyed it. Good, because I'll be spending a lot more time there. #Brexit— Lloyd Blankfein (@lloydblankfein) October 19, 2017
"He's articulating publicly what many CEOs and investors who love working in London have been saying privately, which is that unless they have certainty about what happens after March 29, 2019, they have got to make a plan B," he said.
"He's not bluffing. When I speak to businesses each day, they're not bluffing," Mr Khan said.