Fears were mounting for two more Irish people in New Zealand after the devastating earthquake that crushed a Monaghan man to death in his car.
Authorities have been unable to contact the missing pair who were both thought to have been in Christchurch when the disaster struck.
The Department of Foreign Affairs said it had "serious concerns" for the as yet unidentified Irish nationals after all efforts to get in touch with them failed.
Officials working with their families stressed that there are issues with mobile telephone networks in New Zealand since the tremor tore apart buildings in Christchurch on the south island yesterday, killing at least 75 people.
One of the dead, Eoin McKenna from Co Monaghan, was living in the country for about six years.
Believed to be aged in his forties, he worked as a psychiatric nurse and was a well-known figure in his local GAA. He moved abroad after marrying a woman from New Zealand.
Former school friends said the father-of-two had trained and worked in London and also spent some time in Saudi Arabia, where he met his wife.
Fabian Murphy, an old school friend from St McCartan's College in Monaghan, last met Mr McKenna when he returned home for a short visit in July 2009.
"He was as funny as ever. I have known him since we were four-years-old," Mr Murphy said.
"He was one of the funniest people ever, even in 2009, the night's craic we had was just like old times.
"We'll really miss him."
It is understood the hospital where Mr McKenna worked contacted the family in the Emyvale area of Monaghan to say he had not arrived for work after the powerful 6.3-magnitude quake struck.
Mr McKenna's car was crushed by falling debris.
The Department of Foreign Affairs said it is believed a second man killed in the quake was married to an Irish woman. Officials are working to firmly establish his nationality.
A spokeswoman said they are "pretty sure" everyone on a larger list of about 50 Irish people living in the area are safe but they are awaiting confirmation.
As rescue workers continued to comb through the rubble, thirty-nine bodies were identified at a temporary morgue at the central police station.
There are fears that more than 100 could still be buried - 120 people have been rescued so far.
Vicki Treadell, the British high commissioner to New Zealand, said her staff are in direct touch with the senior police officer in charge of the mortuary where bodies are being taken.
She told the BBC: "My consular manager has kept in regular touch with him, and as and when any of those fatalities are identified as British - if we get that information - we too will be able to confirm whether it is one or more.
"But clearly it would be foolish to speculate at this stage that there are definitely a specific number because that would be pure guesswork, and what we need to do is to deal with the facts so that we don't cause any greater unsettlement and grief than is necessary."
Asked what relatives should do if they are concerned about their loved ones, she said her staff are feeding information back to a call centre in London that is dealing with the majority of calls.
She said if people are in direct touch with their relatives, they should confirm their safety with the authorities.
"We are in touch with various agencies, the Red Cross for example, on the ground, and as soon as we have any news, we are trying to make sure we put it into the system and if there are people we have identified here who are asking us to contact their next of kin, that is what we're doing," she said.
Speaking about the scenes in Christchurch, she said: "It is a confusing scenario. There are, and have continued to be, small aftershocks.
"It is an unstable and fluid environment where the safety of those on the front line is also a concern and a consideration.
"In some of the collapsed buildings we know there are people still alive inside and those are the buildings that are taking the priority of the search and rescue teams to try to get rescues under way but, given that unstable environment and these continuing aftershocks, these are delicate operations."
Since last September's earthquake, the residents of Christchurch have become used to the grim reality of living in a city pummelled by powerful aftershocks on a near weekly basis. But nothing could have prepared them for the destruction wrought by yesterday's quake.