Positivity rate has also soared to as high as 15 per cent in some test centres around the country, the HSE (Health and Safety Executive) added.
The surge comes as the nation’s test and trace service gets underway with more than 20,000 tests being carried out each day.
But HSE chief executive Paul Reid has warned that there are “early indications” that Ireland could “reach above 1000 cases per day towards the end of July.
“So it seems to have accelerated much quicker that we thought it would.
“We are seeing about 15 per cent positivity on some sites across the country.
“But it is spreading.
“It’s not targeted in just a few sites,” he added.
Mr Reid added: “There’s a higher numbers of cases, higher positivity and higher numbers of close contracts, which are accelerating it beyond what might have been predicted.”
He said he has “real concern” over the increase in case numbers, and warned if transmission levels get too high it will also impact the vaccinated population.
“We do know a significant proportion of the population are protected through having been vaccinated.
“But we have a significant portion of the population who aren’t protected,” he said.
There were an additional 994 confirmed cases of Covid-19 in Ireland, the Department of Health said.
As of 8am on Thursday, there were 80 patients in hospital with the disease, of whom 22 were in intensive care units.
Experts are urging those who have not taken up the vaccine to do so. While Tanaiste Leo Varadkar pleaded with those who have not yet got their jabs to treat the pandemic “as seriously as you did at any point”.