Taoiseach Michael Martin has tested negative for Covid-19.
He had been in contact with French President Emanuel Macron who tested postive for the virus.
Mr Martin and Macron both attended a European Council meeting last Thursday and Friday.
A spokesman told The Irish Times that Mr Martin had tested negative after returning from Brussels and that he will now take another test and limit his contacts following the news about Mr Macron.
The presidential Elysee Palace announced that Mr Macron had tested positive on Thursday morning.
It said the president took a test “as soon as the first symptoms appeared”.
The brief statement did not say what symptoms Mr Macron experienced.
It said he would isolate for seven days, adding: “He will continue to work and take care of his activities at a distance.”
The French and Spanish prime ministers are among those self-isolating because they had recent contact with him.
UK Prime Minister Boris Johnson, who had Covid-19 earlier in the year, tweeted his support for the French president.
Mr Johnson said: “Sorry to hear my friend @EmmanuelMacron has tested positive for coronavirus. We are all wishing you a speedy recovery.”
He then repeated the message in French.
Mr Macron also held the French government’s weekly Cabinet meeting on Wednesday in the presence of Prime Minister Jean Castex and other ministers.
Mr Castex’s office said the prime minister is also self-isolating for seven days.
The French presidency confirmed Mr Macron’s trip to Lebanon scheduled for next week is being cancelled.
Mr Macron and other government officials have repeatedly said they have been sticking to strict sanitary protocols during the pandemic, including not shaking hands, wearing a mask and keeping distance from other people.
