Arlene Foster has remained silent on the controversy over social distancing on aircraft, despite the Deputy First Minster and Health Minister both saying they were shocked at images of a crowded Aer Lingus flight between Belfast City and Heathrow.
Michelle O'Neill called the photographs "horrendous" while Robin Swann said they were "frightening" and that the airline appeared "oblivious of any of the regulations."
Aer Lingus said on Tuesday it would be adding an extra flight on each day of operation to reduce passenger numbers.
Mrs O'Neill called on all airlines to do everything possible to stop the spread of Covid-19.
"I think it's important that we look at all these things - and we are," she said.
"The images of all those people on a flight are horrendous.
"It's frightening and it should never be allowed to happen.It's absolutely right for all airlines to take a look at their policies. The issue of airlines needs to be very, very seriously scrutinised."
Health Minister Robin Swann said he was "shocked".
"It was as if they were living in a time before Covid-19, completely oblivious of any of the regulations and the guidance," he added.
"How can they think that what the practice they were actually carrying out was in any way in keeping with the guidance that we have been issuing?
"I think it was a short, sharp shock that they could still be behaving in that manner."
Speaking on current affairs programme The View on April 23, First Minister Arlene Foster said she did not believe there was a need to isolate people flying into Belfast from airports in Great Britain.
She said international travellers coming here via London should self-isolate.
But she added: "I think it would be quite wrong to stop people coming in from the rest of the UK into Northern Ireland and expecting them to self-isolate when they are only travelling within the one country."
The DUP did not respond to a request for further comment from the First Minister.
However, DUP colleague Ian Paisley MP said that any call for flights between Northern Ireland and Great Britain to be stopped would be "the height of lunacy".
"We have to be cautious and careful, but we have to get on with life," he added.
"The alternative is that we do not leave Northern Ireland ever.
"Total reassurance cannot be given.
"I think we have personal responsibility in this. We've been told what we have to do.
"Stopping air travel is not going to stop the spread of the virus - the virus is already here," he said.
"The logical conclusion of doing so would be that we all lock ourselves up and never come out again."
As well as an second flight between Belfast and Heathrow, Aer Lingus has advised all customers due to travel on the route to give themselves additional time to check in, as changes to the boarding procedure will be introduced and more luggage will be checked into the hold.
"It is expected that this additional frequency will result in reduced loads on each flight," the airline said.