The Northern Ireland Statistics and Research Agency recorded 664 deaths up to 15 May in Northern Ireland.
That is 192 more than the Department of Health figures for the same period.
It comes as the The Public Health Agency has published its first monthly report on the key trends and characteristics of Covid-19 in Northern Ireland.
It reveals that up to May 17, there had been 4,469 laboratory-confirmed cases.
The report also reveals that testing swabs taken between December 27 and March 12 did not produce any positive results, which the PHA said indicates the virus was not circulating undetected in Northern Ireland before the first case was confirmed at the end of February.
Health Minister Robin Swann said he hopes the monthly report will "ensure that there is the maximum possible transparency" around coronavirus.
"The data helps us to track and understand the virus and its impact both on the community and the health and social care system," he said.
"The statistics also tell a human story of how the virus has left its tragic mark on families and communities who have lost loved ones.
"The valuable and detailed analysis contained within the monthly bulletin will help us to develop our plans for the vital recovery period as we start to re-engage our health and social care services."
Watch our report here: