An investigation has determined that the fire was caused by a mattress catching alight in the converted garage where the couple lived at the side of their house at Glenvara Park, Knocklyon.

The cause of the blaze has not yet been conclusively determined but it is thought a cigarette could have been to blame.

Sheila Power, who was in her 50s, had been in a wheelchair since suffering a stroke 10 years ago. It is thought she woke up when the fire started and tried to get to her wheelchair, knocking it over in the process. Her husband, a former taxi driver in his 60s, also woke up but was overcome by smoke and could not save his wife.

The fire brigade found the couple dead on the floor clutching each other when they entered the garage at around 3.30pm.

Neighbours had become concerned at not having seen the pair for a few days. The Powers were parents of a grown-up son and daughter who both lived locally.

A garda source said: "We are not looking for anybody else in connection with the tragedy. Both the house and garage were locked and there had not been any forced entry. The fire probably happened in the evening or at night so neighbours would not have been able to see flames or smoke.

The mattress would have gone up in seconds and the smoke would have quickly overcome the couple. They would not have been awake very long when it overcame them so they did not suffer."