EU foreign ministers are also holding talks on Ukraine, Syria and Iran
Britain and the European Union have agreed a deal on the Brexit transition period.
It will end in December 2020, and will allow talks on a future trade deal to begin later this week.
It will also allow citizens who arrive in the UK before 2021 the same rights as those already there.
The British Brexit Secretary David Davis said there must be a fair and equal transition.
"We agree on the need to include legal text detailing the backstop solution for the border between Northern Ireland and Ireland in the withdrawal agreement that is acceptable to both sides.
"But it remains our intention to achieve a partnership that is so close as to not require specific measures in relation to Northern Ireland".
"We're establishing a joint committee made up of representatives of of the United Kingdom and the European Union.
"This committee will provide a way to resolve concerns as they arise - and will underpinned by a clear commitment from both sides to act in good faith."
However, the EU's chief Brexit negotiator Michel Barnier said there is still some work to be done on the draft treaty surrounding leaving.
In a tweet he said: "Backstop solution must apply unless and until another solution is found".
Tánaiste Simon Coveney is attending the EU Council meeting in Brussels, where he also met with Mr Barnier.
Good to see @simoncoveney again before my meeting with @DavidDavisMP this morning. Full support for Ireland. Backstop solution must apply unless and until another solution is found #Brexit pic.twitter.com/iV9aaNphHL— Michel Barnier (@MichelBarnier) March 19, 2018
Mr Coveney said earlier this was an "important day" in Brexit negotiations in the build up to an EU Council meeting later this week.
He also said there would be "no backsliding" on the issue of the Irish border.
On early flight to Brussels for meeting with @MichelBarnier this morning - important day in #brexit negotiations in build up to EU Council on Thurs/Fri - no backsliding on Irish Border issue remains clear focus to facilitate progress on other issues.— Simon Coveney (@simoncoveney) March 19, 2018
Mr Coveney is also discussing the recent nerve-agent attack in Salisbury in the UK, and the situation in Syria, with other foreign ministers.
As international chemical weapons experts arrive in Britain to investigate the Salisbury attack, EU foreign ministers are formulating their response in Brussels.
The team of independent investigators from the Organisation for the Prohibition of Chemical Weapons (OPCW) are arriving in Britain from The Hague.
They were invited by the British government last week to verify analysis of the nerve agent used in the March 4th attack.
They are meeting officials from the UK's Defence Science and Technology Laboratory and police to talk about the process for collecting samples, including environmental ones.
The samples will then be sent to "highly reputable international laboratories" selected by the OPCW for testing.
Speaking ahead of the talks, Mr Coveney said Ireland fully supports the UK's efforts to ensure the perpetrators of "this heinous crime" can be held accountable.
He said: "All EU member states are in complete solidarity with the UK on this issue, which will be discussed at the European Council later this week."
Former Russian spy Sergei Skripal and his daughter Yulia remain in critical condition after being poisoned with a nerve agent.
The Tánaiste is also discussing the situation in Ukraine, as well as developments in Syria and in Iran.
Speaking on Sunday, Mr Coveney said: "Today, on the fourth anniversary of the illegal annexation of Crimea and the city of Sevastopol, I reiterate Ireland’s steadfast support for Ukraine’s sovereignty, independence and territorial integrity.
"We do not recognise the annexation and we continue to call on the Russian Federation to observe the fundamental principles of international law and restore Ukraine’s internationally recognised borders."
On the worsening human rights situation in Crimea, he said: "The deterioration of the human rights situation since the annexation is deeply concerning.
"I call on the Russian Federation to guarantee that freedom of expression, religion, belief and the right to peaceful assembly can be exercised by citizens of Crimea without discrimination on any grounds.
"All allegations of human rights violations involving political prisoners, human rights defenders and civil society activists must be fully and properly investigated."
Ministers are also having an informal lunch with the foreign minister of the Republic of Korea.
With reporting from Jack Quann