DUP leader Arlene Foster has hit out at Sinn Féin president Mary Lou McDonald for 'constitutional navel-gazing' amid the Covid-19 pandemic.
Mrs McDonald described the pandemic in a weekend newspaper article as an 'accelerant' to a united Ireland.
The Dublin TD has been highly critical of the British Government's approach to Covid-19 and described the lack of a single health policy across the island of Ireland as 'astonishing'.
Her comments came after junior minister Declan Kearney accused 'someunionists' in Northern Ireland of putting the economy ahead of public health,claiming there was a push to relax lockdown rules to help the economy.
Mrs Foster described the comments as 'regrettable'.
"I think the most important job for me as First Minister of Northern Irelandis to protect lives, to save lives, to make sure that our National HealthService, that great British institution, is not in any way overwhelmed by whatis going on," she said on Monday.
"So I do think it is regrettable that other leaders are interested inconstitutional navel-gazing at this time. I think it would be important for usto look back with hindsight when we're not in the middle of a pandemic.
But for others, their priorities lie elsewhere, I think that is regrettable.
"As I say, my most important job at the moment is to warn, to protect, andthat's what I'm focused on doing."
Ulster Unionist Party leader Steve Aiken also criticised Mrs McDonald andaccused her of 'attempting to advance' her party's political ideology.
He said: "The message from the health minister Robin Swann is clear. We cannot afford to be complacent about social distancing, otherwise we risk seeing the number of deaths rising. That should be our focus."
Splits have emerged between the DUP and Sinn Féin within the Northern Ireland Executive, with Sinn Féin's Michelle O'Neill speaking out over testing and personal protective equipment, while last week the parties disagreed over whether to reopen graveyards.
Mrs McDonald told the Sunday Times that Ms O'Neill "had to have some pretty tough conversations" over health policy.
She said: "When Brexit happened, people said this is an accelerant in terms of the unity debate, because it was so obvious with the danger to the border.
"We have an all-Ireland single policy for animal health but not for publichealth.
"Everything we do to keep people safe has to be on the understanding we are a single population on a small island and have to look after each other.
"I think the fact that Boris Johnson and the British Government opted early on for the herd immunity approach meant that Michelle O'Neill had to have some pretty tough conversations to get the northern system in tandem with what was happening in the South.
"Yet again we see how vulnerable we are when we have two jurisdictions, two systems, on the island."