© Irish TimesLeo Varadkar speaking in the Dáil
"We should not assume that it came here from Italy in late February just because the first confirmed case did so," he told the Dáil.
Mr Varadkar said retrospective testing suggested the virus was circulation in France as far back as December last year, before it was even had a name or test.
This in some ways "was not surprising as France was well connected to China with dozens of flights every day and Ireland is very connected to France".
More research was needed and time would tell, he added.
In sharp exchanges during a debate on the coronavirus crisis, Mr Varadkar confirmed the pandemic unemployment payment (PUP) of €350 a week would continue beyond mid-June as he rounded on Sinn Féin leader Mary Lou McDonald, accusing her of being "two-faced".
Comparing her party's actions in the North to the behaviour of the US president, Mr Varadkar said Sinn Féin's ministers in Northern Ireland "promote the fact that they hand food parcels to the poor - reminiscent to me of Donald Trump, handing out toilet roll after the hurricane hit the islands in the Caribbean".
Ms McDonald had hit out at comments by Minister for Finance Paschal Donohoe that the PUP could not continue forever and she said that to cut it would be to "to pull the rug from under the feet of so many and force those who can least afford it to pay for the economic fallout from this emergency".
During the Dáil debate, she said suggestions of the payment being ended showed that "Fine Gael remains out of touch with the lives of workers and families, with those bearing the brunt of this economic shock".
She said Mr Donohoe's comments "sent a shiver of apprehension down with the spines of those who suffered untold hardship as a result of the vicious cuts meted out by both Fine Gael and Fianna Fáil over the past decade".
Comment: Western economies crippled by corruption and austerity were dealt the death blow with this contrived coronavirus crisis.
But the Taoiseach described the payment as an unprecedented action, and said it was not affordable for it to last forever.
However "it will need to continue. At least until people have the opportunity to return to their jobs.
"And for the vast majority that won't be possible before mid-June. And so yes it will need to be extended beyond mid-June".
But accusing Ms McDonald of becoming "so party political in her contributions" he said she was being "so two-faced and so fundamentally dishonest".
He compared the State's social welfare system to that in the North where Sinn Féin was in office and said the payment was £100 a week with nothing for the self-employed until June.
He claimed Sinn Féin "boasts" about giving food parcels. "I'd be ashamed to do something like that."
But Ms McDonald said grants of £10,000 or £25,000 were being made to businesses in the North across all sectors, and that in the six counties the payment was "far greater than the entire €250million, which is pretty miserly that's been set out here".
She pointed out that it was not just in the North that people were struggling noting that St Vincent de Paul launched a fundraising campaign, an acknowledgement of the fact that we have a lot of needy people".
The Taoiseach said the Government funded food banks and had done so for a long time but but they did not "post on Facebook pictures of our ministers and visiting them, and handing out food to the poor".
Sinn Féin was doing "more for business than they are doing for the employed in the North".
Mr Varadkar also rejected criticism that Ireland was slower to ease lockdown measures than other countries.
"It is true we are slower than countries much less affected than us like Australia, New Zealand, and slower than countries much worse affected than us, like Spain and Belgium."
But the Taoiseach said Ireland was testing at a much higher rate than in New Zealand or Australia and was between third and seventh in the world for testing ahead of Germany and of other countries including South Korea.
He said "this is a decision the Government made" and "it's one we stand over".
He said he would rather be in a situation where the State might accelerate the pace of return than having to pause or reverse or re-impose restrictions, like some other countries. To have to do so would profoundly affect morale, Mr Varadkar said.
He said the curve has been flattened and plateaued, but society's grief had not. "The stakes are too high to rush things now."
Comment: We can now add Ireland to the list of countries that have admitted that the coronavirus was in circulation months before and therefore the lockdown was all for nought: