Almost a third of people classed as having died from Covid-19 in Northern Ireland did not test positive for the virus.
According to the Northern Ireland Statistics and Research Agency (Nisra), as of July 3 835 people had been registered as having been killed by coronavirus.
The Department of Health (DoH) total, however, is 556. This is because Nisra's figure includes anyone whose death certificate mentions Covid-19, whether they had tested positive for the virus or not.
The DoH death figure is compiled using data from the five health trusts, which class a death as being coronavirus-related if it occurred within 28 days of a positive test, even if the virus was not the main cause of death.
The department detailed how the two sets of statistics were generated in response to an Assembly question by TUV leader Jim Allister.
"This figure is based on the differencing of two key but unlinked sources and therefore may be subject to some error," it said.
"Nisra publishes weekly death statistics. These include the number of Covid-related deaths, identified by any mention of Covid-19 on the death certificate. They include suspect and probable cases."
Mr Allister told Sunday Life the Nisra figure inflated the number of coronavirus-related deaths.
He added that the truth probably lay somewhere between the two totals.
"It's clear that what Nisra is relying on is what's on the death certificate and there can be multiple things on the death certificate," Mr Allister said.
"Leave Covid-19 out of it and you could have heart failure, respiratory failure, pneumonia...all those would be possibilities.
"Likewise, they have been putting (coronavirus) on death certificates if patients have been showing any symptoms of Covid-19.
"(But) those people have never been tested and therefore you cannot say that they died of Covid-19.
"That has inflated the figures because if Covid-19 appears at all, it is counted as a Covid-19 death.
"You can only really say with certainty that it was Covid-19 when the person who is dead has tested positive for Covid-19.
"I suspect the truth is somewhere between the two (figures), in that there will be people who have been certified dead for various reasons where Covid-19 might actually have been the killer."
In its weekly deaths update, Nisra explained why there was a difference between its figures and those released by the DoH.
"Nisra's weekly provisional death statistics, which are based on death registration information collected by the General Register Office, count all deaths where Covid-19 was mentioned on the death certificate by the doctor who certified the death, whether or not Covid-19 was the primary underlying cause of death," it said.
"The figures include cases where the doctor noted that there was suspected or probable coronavirus infection involved in the death.
"As a result, the weekly totals will usually be higher than the relevant daily figures because the DoH daily updates only include those who have tested positive for the virus."