The Cypriot airline, whose plane crashed in Athens in Greece on Sunday killing all 121 people on board, has said the same plane had previous cabin pressure problems.
Experts say it is likely that a sudden loss of oxygen killed most of those on board the aircraft before it crashed.
The official coroner has said that at least 25 of those killed were alive at the moment of impact, including the co-pilot and an air hostess, though not necessarily conscious.
In Ireland, a Book of Condolence will be opened tomorrow and Thursday at the Cypriot Embassy in Dublin in memory of those killed in the crash.
The investigation into the crash is continuing. Police in Cyprus have seized documents at the offices of the airline company, Helios Airways, on foot of warrants issued by the Cypriot Attorney General.
Separately, a man who claimed to have received a text message from a cousin on the airliner before it crashed has been arrested.
Police in northern Greece detained the 32-year-old man yesterday, saying the text message was a hoax.
The man had telephoned a Greek television station minutes after the plane crashed.
He claimed he had received a message saying: 'We're cold. The pilot is blue. We're going to die.'
It is believed the unnamed man, who was arrested in the north Greek city of Salonika, has been charged with wasting police time.
It has been reported that he has confessed to making up the story that he received a text message from a cousin on flight 522.
Police became suspicious when it turned out the man's supposed cousin was not on any passenger list.
But at the time the information fuelled speculation that the crash may have been caused by a sudden and fatal drop in cabin pressure.
Meanwhile, Cyprus is holding a second day of national mourning.
