Hundreds of coronavirus test appointments have been cancelled due to a shortage of testing kits, it has emerged.
Test centres across the country were forced to close yesterday after medical staff ran out of medical equipment used to test for the virus.
Most testing sites, but not all, are expected to reopen today.
Those people who were due to be tested yesterday have been given new appointments.
The country's largest test centres, Páirc Uí Chaoimh in Cork and Tallaght Stadium in Dublin, were both closed after medics ran out of testing kits.
Páirc Uí Chaoimh will re-open today with a reduced service, said the HSE's Chief Operations Officer Anne O'Connor this morning on RTÉ's Morning Ireland.
"We are getting supply back out, there will be a level of testing, I don't know exactly in each test centre what that level is, but we know we will have a reduced service today, and we will be back at a higher level of service again tomorrow.
"Some stock arrived yesterday and last night, we have more arriving today, so we will be sending that out across our system," she added.
In Tallaght, people attending scheduled appointments were turned away when they arrived at the centre.
Several people who have potential symptoms of the virus and are in priority groups for testing turned up at the stadium and only then learned their appointments would be rescheduled.
One of those involved said there was no sign or notification at the stadium and they only found out it was closed after contacting the HSE.
It is understood a text message alerting people to the cancellation of their test failed to send to some who were scheduled for an appointment at the football stadium.
The HSE sent another message apologising for the mix-up yesterday morning.
However, some of those with appointments had already attended the testing centre.
The HSE revealed it was closing Páirc Uí Chaoimh due to a lack of testing equipment during a press briefing.
The Cork testing centre is due to reopen today.
A Government source said the HSE was up to date with referrals in Cork and Kerry and would offer appointments tomorrow for any outstanding referrals.
Following a series of queries, the HSE revealed testing had been scaled back due to a lack of specialised testing equipment.
"There has been limited testing nationally today as the supply of testing materials has been limited, a further order is due in this afternoon and will be distributed," a spokesperson said.
There is a worldwide shortage in testing kits and the reagent used to test the sample from those thought to have contracted the virus.
The Government was expecting a significant shipment of new testing kits and personal protection equipment (PPE) for healthcare workers yesterday evening.
More than €26m worth of PPE will be delivered, totalling 1.6 million masks, 400,000 eye protections, 265,000 gowns and 254,000 gloves.
Almost 5,000 people are tested a day in Ireland for the coronavirus and more than 50 testing sites are being set up nationwide. Yesterday, the HSE said there was a backlog of 15,500 people waiting to be tested since the Government changed the criteria for receiving an appointment in the middle of last week.
Around 10,700 people have received an appointment and 4,800 are waiting for a test date. More than 33,000 people have been tested for the coronavirus since the start of the public health crisis.