A Somali journalist told the NewsMail he saw Mr Brennan and Ms Lindhout board a small chartered plane early on Thursday, where they were headed to neighbouring Kenya.
"It was a special flight to Nairobi; it was just the two of them," Mohamed Omar Hussein said.
The plane reportedly took off about 3.45pm Queensland time, about 12 hours after they were released.
Mr Brennan and Ms Lindhout made no public statement and journalists waiting at the airport were not able to speak to the pair because they were in a convoy of vehicles full of government soldiers and African Union peacekeepers.Earlier, Mr Brennan's family spoke of their joy at his release.
Mr Brennan's sister-in-law, Kellie Brennan, fronted a press conference in Sydney this morning and delivered a statement on behalf of the family.
"It’s very hard to express the overwhelming sense of joy that we have today as a family at the news of Nigel and Amanda’s release," a clearly emotional Ms Brennan said.
She said it had been an "unbelievably harrowing and wearing ordeal" for the family since Mr Brennan and Ms Lindhout's capture on August 23 last year.
"Nothing could have prepared us for what we have gone through since Nigel’s capture," Ms Brennan said.
She said her brother-in-law would take "plenty of time" to readjust to normal life following his 15 months in captivity, and that he would undergo a medical check once he was in a safe location.
"In terms of Nigel’s physical health, he will receive a full medical check once they are in a safe location," Ms Brennan said.
"I cannot stress enough that they are not out of harm’s way. As soon as he is safe and fit to fly he will be coming home."Mr Brennan had briefly told Reuters he was chained and beaten as he endured a 15-month wait for his release.
He said he was kept in chains and had been isolated from Ms Lindhout for 10 months after they had tried to escape.
"Locked in a room, very little light. I haven't been able to exercise at all. You know, simple things like being told not to smile, not to laugh - not that there was much to laugh about," he said.
"But my friend Amanda had a pretty rough time, I know that. She was severely beaten and we were both tortured both mentally and physically.
"Being pistol-whipped is sort of torture, being completely stripped of everything and then locked in a room, no one to speak to, is a form of torture really."
Mr Brennan and Ms Lindhout were released by the Somalian militants after 15 months in captivity.
They are reported to be in good health.
Mr Brennan's parents have been in Somalia for the past few weeks in a desperate bid to secure his release, but there are few details as yet of how this was achieved.
A spokesman from the Department of Foreign Affairs and Trade said no comment would be made until Mr Brennan had left Somalia.
Somali journalist and interpreter Abdifatah Mohammed Elmi, and their two Somali drivers were also kidnapped at the same time as Mr Brennan and Ms Lindhout, but they were released in January.
The group were taken following a trip to visit displaced people outside the city. The alarm was raised when they failed to return to their hotel after a few hours.
Mr Brennan had only been in the country for a week when the kidnapping happened.
Read the full story in tomorrow's NewsMail. Check back for updates.
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