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Lukman Thalib, 58, and Ismail Talib, 24, were detained at their home in Qatar on 27 July by a group of plain clothes officers, Professor Thalib's daughter Maryam Talib told SBS News last month.
London-based advocacy group CAGE, which was supporting the family, said they believe the arrests were linked to allegations surrounding another of Professor Thalib's sons.
But on Friday, CAGE said the pair had arrived safely arrived in Turkey, where Ms Talib lives, after being released from the detention centre last week. It is still unclear why the men were arrested and the reason for their sudden release.