Leo Varadkar has said it's "very possible" that the coronavirus was in Ireland last December.
The Taoiseach was speaking in the Dail when he referenced reports suggesting that France may have had its first case before the New Year.
The Fine Gael leader said: "We are still learning about this virus.
"It's noteworthy that initial reports suggest that from retrospective testing, that the virus was circulating in France as far back as December last year.
"That's before the virus even had a name or a test for it.
"In some ways, this is not surprising as France is well connected to China with dozens of flights every day, and Ireland is well connected to France.
"Indeed, it is very possible that this virus was already in Ireland last year, or January this year.
"And we can not assume that it came here from Italy in late February, just because the first confirmed case did so.
"Further research and retrospective testing will give us a better idea and time will tell."
It comes as Mr Varadkar has promised that the €350 coronavirus support payments schemes will continue past their June deadline.
The Taoiseach told the Dail this afternoon that the supports will be extended past mid-June, and that no decision has yet been made on when the €350 amount will be cut.
He said it is necessary to keep up the payments to over one million of the Irish workforce because we are not near the end of this emergency yet.
Mr Varadkar said: “It cannot last forever, however, it will need to continue at least until people have the chance to return to their jobs and for the vast majority of people that won’t be before mid-June, so yes, it will need to be extended beyond mid-June and I am happy to say that here in the House today.”
Meanwhile, Mr Varadkar also used his Dail time to launch an astonishing attack on Sinn Fein leader Mary Lou McDonald, calling her “two-faced and dishonest”.
The blistering barrage from the Taoiseach came out of the blue during questions on coronavirus in the Dail this afternoon.
And it was more like a political leader in electioneering mode, which underlines the fact that a second election this year is still on the cards.
The Taoiseach accused Ms McDonald of saying one thing in the Dail while preaching the opposite in the Northern Ireland Assembly.
He criticised Sinn Fein for ministers handing out food bags in the North and posting pictures on Facebook “boasting about it.”
He said his Government manages food banks in the South and never looks for credit.
And Mr Varadkar compared Sinn Fein’s actions during the coronavirus epidemic to US President Donald Trump handing out toilet roll after hurricane disasters.
