Agreement between the UK and EU on sharing trade data is a "significant building block" to reach a deal on the NI Protocol, Micheál Martin has said.
The tanaiste (Irish deputy PM) and foreign affairs minister was speaking in Brussels after meeting the EU's chief negotiator Maros Šefčovič.
He will hold separate talks with the Northern Ireland secretary on Thursday.
He said: "I've always believed this could be solved through negotiations so long as they are given space and time."
However, he cautioned that there needed to be a "step-by-step" approach and that he did not want to give a running commentary about the level of detail wider discussions are currently at.
"The political will I think is now there, that doesn't take away from the complexity of the issues, but the will is there now on all sides," added Mr Martin.
Very useful discussion on the Protocol with @MarosSefcovic today.
He has our full support as hard work continues to find joint solutions in the EU-UK discussions.
Encouraged by the new positive momentum. pic.twitter.com/EFuaEJgKxr
The tanaiste repeated his call for the Democratic Unionist Party (DUP) to re-enter an executive at Stormont without delay, but said he appreciated the concerns raised by unionists about the operation of the protocol.
DUP MP Gregory Campbell said the agreement on sharing trade data was being "trumpeted as some sort of breakthrough" but did not address the party's concerns over the protocol.
"At the bottom line from all of this there are two fundamental issues that flow from the protocol problem, one is the constitutional political implications that it provides for Northern Ireland, the other is the trading implications," he said.
He added: "We need to hear the details of what this does for trading. It might just shift the burden slightly but it doesn't resolve the overall problem.
"The only good thing that comes out of yesterday is that if minds are starting to be concentrated now on the need for a resolution it has to be the right resolution."
On Wednesday, UK Foreign Secretary James Cleverly will travel to Belfast to hold talks with parties about the deal on sharing trade data.
The Labour leader Sir Keir Starmer and Taoiseach (Irish Prime Minister) Leo Varadkar are both set to hold their own separate talks in Northern Ireland on Thursday.
Northern Ireland Secretary Chris Heaton-Harris will also host discussions with parties on Wednesday.
It is expected that progress on the protocol and the ongoing Stormont stalemate will be discussed.
Stormont has not had a fully-functioning executive since February last year, when the DUP withdrew as part of its ongoing protest against the protocol.
The protocol is a part of the UK-EU Brexit deal that keeps Northern Ireland aligned with some EU trade rules.
It keeps Northern Ireland aligned with the EU's single market for goods, avoiding the need for a hard border with the Irish Republic after Brexit.
However, it also creates a new trade border between Northern Ireland and the rest of the UK, something the EU accepts is causing difficulties for many businesses.
Some unionists say it is also undermining Northern Ireland's place in the UK.
The UK says the protocol is not working and plans to override most of the agreement if the EU does not agree to changes.
On Monday, the European Union (EU) and UK reached an agreement which would give the EU access to UK IT systems giving detailed information about goods flowing from Great Britain to Northern Ireland.
In a joint statement, the EU and UK said the agreement on trade data was "a critical prerequisite to building trust and providing assurance, and provided a new basis for EU-UK discussions".
It came after a meeting between James Cleverly, Chris Heaton-Harris and Mr Šefčovič.
The men are set to meet again next week.
Earlier, Sinn Féin's Declan Kearney said the agreement on sharing trade data was an important development.
"It demonstrates that it's possible to find the flexibilities and it would be my firm hope that we will now see further work made in finding a pragmatic and durable agreement [on the protocol] into the future," Mr Kearney told Good Morning Ulster.
"Hopefully the discussions that are scheduled for tomorrow and Thursday will bring further confidence to the process and move us closer to the point where we've seen a resolution to all of the remaining issues which have kept this impasse in place."
Stephen Farry of the Alliance Party said it was "substantive progress".
"This is a powerful foundation, it builds that partnership, but we need to see much more progress over the coming weeks.
"I dare say there's a sense of urgency here given the perilous state of Northern Ireland, we need to see the assembly restored as soon as possible, so I think we need to see a much more comprehensive agreement as soon as possible."
UK and EU reach agreement on trade data sharing
A simple guide to the Northern Ireland Protocol
Seven dead in second California shooting in days
Rioter who propped feet on Pelosi's desk found guilty
Erdogan tells Sweden not to expect Nato bid support
Men must stand up for Afghan women – professor
Hero who disarmed gunman had never seen a real gun
Eight-year-old Indian diamond heiress who became a nun
What you need to know about Nigeria's elections
Inside the Atlas Lions – the Englishman behind Morocco's epic run
What’s the future of India's sinking Himalayan town?
The bacteria controlling your brain
What we know about the Monterey Park victims
Residents turn against Russia in liberated Lyman
The simple error that 16% of us make
Gen Z's latest surprising obsession
A return to old-school Canadian glamour
© 2023 BBC. The BBC is not responsible for the content of external sites. Read about our approach to external linking.