Undertakers have said they are having uncomfortable conversations with bereaved Catholic families after the Church put a limit on the number of mourners at funeral services.
In a bid to control the spread of coronavirus, All Ireland Primate Archbishop Eamon Martin announced a limit of 100 people attending both Requiem Masses and weddings across the island of Ireland.
In Northern Ireland the two largest Protestant Churches are following official UK guidance, which means they have no such restrictions.
However, the Church of Ireland and Presbyterian Church are abiding by the restrictions in the Republic.
Sean Carr, an undertaker in Londonderry, where the tradition is for large funerals, said he hopes Catholic families affected will understand.
He said: "I have already had to go to families who were expecting to have funerals on Sundays during the regular Sunday Mass but that isn't happening now.
"Parish priests are doing their best to work with families but it is going to be very hard on any family to restrict the number attending a funeral to 100.
"What happens if it is a funeral for someone who came from a big family? It wouldn't take much to reach 100 people and it will be hard to ask other people not to come to the chapel.
"I think the best solution will be if the family asked people to watch the funeral via a webcam which means you can see what is going on in the chapel via any computer and then those who couldn't come to the chapel could gather at the graveside."
Mr Carr said the uncertainty over funerals is reflective of the confusing advice being issued by the bodies governing his profession.
"The Irish Association of Funeral Directors is advising that if someone dies from the virus, to put them in a coffin, take them straight to the cemetery or crematorium with no church service or wake," he said.
"This is the complete opposite to the British National Association of Funeral Directors who are saying you can embalm the body providing you take all personal protection precautions.
"They are saying have a wake but encourage the family not to touch the remains.
"I have to be honest, I would find it extremely difficult if not impossible to say to a family: 'You can't see your loved one, I am taking them straight to the cemetery.'"
The Presbyterian Church said that "it is vital that we follow the advice and comply with the specific recommendations given by the HSE in the Republic of Ireland and Public Health Agency (PCA) in Northern Ireland".
"For instance, in relation to the Taoiseach's guidance that indoor gatherings of more than 100 people and outdoor gatherings of more than 500 should not take place, we emphasised the need for this to be followed in all circumstances," the Clerk of the General Assembly, Rev Trevor Gribben, said.
Rev Gribben added: "This at present does not apply to our congregations in Northern Ireland."