Taoiseach Micheal Martin has said it would be a "significant failure" if no Brexit deal was agreed.
Negotiations resumed in Brussels on Sunday after Boris Johnson and European Commission president Ursula von der Leyen gave the green light for talks to resume.
The discussions on reaching a trade deal are entering their final days, with both sides hoping to overcome significant differences on fair competition and fishing rights.
Mr Martin said: "Overall I think it is in the best interests of all concerned that a proper trade deal is agreed.
"Our respective economies would suffer, unnecessarily in my view, in the event of a no-deal.
"A deal can be arrived at.
"It would be a significant failure if we were to end up with no deal."
He told media in Cork just days remained to clinch an accord as they move towards the end of the year.
There is an EU Council meeting of leaders towards the latter part of this week.
If there is no deal by the end of the Brexit transition period at the end of the month, then Britain will leave the single market and the customs union and begin trading with the EU on World Trade Organisation terms, with the imposition of tariffs and quotas.
Any accord has to be ratified by both Houses of Parliament in the UK and the European Parliament, as well as signed off by the EU leaders.
There had been hopes that could happen at a two-day summit in the Belgian capital starting on Thursday - their final scheduled gathering of the year - but the timetable is looking increasingly tight.
Ireland stands to be among the European countries hardest hit by no deal since a large proportion of its exports go to Britain and it uses the UK truck route "land bridge" via Dover for goods arriving from Europe.