The HSE says the suspension of walk-in Covid testing centres could last for the next two weeks.
It's aiming to reduce queues at sites after demand rose by more than a third in the last 48 hours.
The increase is being driven by under 14s coming forward following the return of schools.
Dermot Monaghan is the Head of Service Primary Care in CHO 1, which covers Cavan, Donegal, Leitrim, Monaghan and Sligo.
He says "the decision was made nationally to pause walk-in testing and encourage people to use the self-referral online system", which will reduce waiting times and allow the centres to run more smoothly.
He added that the pausing of walk-in testing may continue for the rest of the week and over the weekend if the numbers presenting for testing continues to be high.
Niamh O'Beirne, the HSE's national lead for testing and tracing, says people will need to book a test for the next while: