The extraordinary bravery of a young woman who tried to rescue her father and two brothers - one of them a top Ulster rugby player - when they were overcome by killer fumes has emerged.

Emma Spence twice climbed into a manhole and then down into a slurry tank on the family farm near Hillsborough, Co Down, where her father Noel, 68, and brothers, Graham, 30, and Nevin, 22, all died trying to save each other.

Graham first lowered a ladder into the manhole to retrieve a pet dog which disappeared into the tank, according to Edwin Poots, a friend and near neighbour.

Graham's father then went in to try to save his son and he was followed by Nevin, a member of the Ulster rugby squad, when he realised the other two were in danger.

Miss Spence, an artist, then went down and managed to pull her father on to the ladder where she was assisted by neighbours. They immediately tried to resuscitate Noel. Miss Spence then went back a second time and found Graham in the tank lying in two to three feet of slurry.

But she was then overcome by the odourless fumes and had to be pulled free by the frantic neighbours who ran to the tank after hearing the calls for help.

Details of Miss Spence's dramatic rescue efforts and the farming tragedy which shocked Ireland emerged as relatives and friends prepared for the funerals of the three men in Ballynahinch, Co Down.

Mr Poots, a health minister in the Northern Ireland Executive, said: "Emma risked her own life to try and save her father and brothers. Physically I don't know how she managed it because her dad is a big man. With the weight of the slurry and so on, she needed to muster unbelievable strength to get him pulled up.

"And then she went back in again, risking her life a second time. It is maybe some comfort to the family she didn't lose her life. She was incredibly brave."

Health and safety experts are carrying out an investigation into Saturday's tragedy.