Irish aid worker Sharon Commins arrived back in Dublin last night, free at last after three and a half months as a hostage of bandits in the mountains of Darfur, in western Sudan.

Commins, 32, and her Ugandan colleague Hilda Kawuki, 42, were seized from the compound of Goal, an Irish aid agency, in July, when three gunmen burst in and held guns to their heads.

They were guarded by up to 18 men who went through the motions of executing them. "There were mock assassinations on a few occasions, so it was extremely scary," Commins said.

"We'd be told to kneel and they would shoot around us. Obviously the first time that happened, we thought we were actually going to be shot. And each time we think: okay, I hope it's a mock. But you never know. None of these guys wear glasses so you are not even sure how accurate their sight is, so it was just an extremely dangerous situation to be in."

Commins said that it was the moral support the pair gave each other that enabled them to survive the ordeal. "We prayed together and tried to keep each other strong."

They were moved between four different mountain camps with only two blankets for shelter.

They were fed twice a day but given very little water, and were only allowed to wash once a fortnight.

She said they owed their lives to their captors' continued hopes of obtaining a ransom - but as the weeks passed without payment, their situation became more precarious.

"We were never confident that we would be kept alive."