The recording of the number of people who have died with coronavirus is being investigated after a Welsh health board failed to report numbers daily.
Betsi Cadwaladr health board reported 84 deaths in the north Wales area on Thursday.
It made it look like Wales had seen the biggest daily jump in confirmed deaths to date - 110 - but it included Betsi's figures which were for a whole month.
The health board said the delay was due to issues with its reporting system.
First Minister Mark Drakeford said while the delayed reports did "not change the overall picture" it was important "accurate information" was reported and the system was being investigated.
Earlier on Friday, another 110 people in Wales were confirmed to have died with coronavirus - taking the total number to 751 - by Public Health Wales (PHW).
The sudden increase in numbers - compared to 17 additional deaths reported on Thursday - included 84 retrospectively deaths confirmed to be linked to Covid-19 between 20 March and 22 April in the Betsi Cadwaladr area of north Wales.
In a statement, the board said: "Details of the number of deaths in north Wales were reported in public for the first time today.
"Due to issues identified in our reporting system, today's update includes an accumulation of cases where a patient has died while also testing positive for Covid-19.
"All data on cases of covid-19 and deaths have been recorded correctly, and the issue identified relates to how this data is shared. This issue has now been resolved."
Sian Gwenllian, Plaid Cymru assembly member for Arfon, said the delay in reporting the deaths was "alarming".
"A full picture of the outbreak is essential to maintain public confidence and to inform ministers on crucial decisions such as any easing of the lockdown," she said.
Mr Drakeford said the whole system was now being investigated, so that the government could "confidently" say that the figures being reported "represent an accurate picture in every part of Wales".
North Wales Conservative AM Mark Isherwood said he was "concerned as to how this may have skewed the overall figures and the approach to combatting coronavirus".
"It smacks of incompetence of the highest level," he added.
PHW has repeatedly warned the number of deaths could be higher than figures showed, as they only included the deaths formally reported to them, those who died in hospitals, and some care homes, and whose tests were analysed in a lab.