Iran has extended the release of US citizen Siamak Namazi by three days, his brother said on Saturday.
Mr Namazi, a 51-year-old Iranian-American, is the longest-serving of the four Iranian-Americans held in Tehran.
He was detained in October 2015 with his father Baquer Namazi, a former Unicef official, under convictions for espionage.
Both deny the allegations.
Siamak Namazi is still barred from travelling and could be returned to custody at any time.
He was granted release from prison after his father, who was serving his sentence under house arrest, was allowed to travel to Abu Dhabi for medical treatment.
Siamak's brother, Babak Namazi, said in a statement on Saturday that Iranian authorities had granted his sibling a further three-day furlough and that he hoped a longer extension would follow, AFP reported.
“We hope and pray that he will be granted his full freedom soon so that our family can finally be made whole again,” he said.
He added that his father, counter to the recommendations of his Iranian physicians, would not undergo surgery for now to clear a life-threatening blockage in his left carotid artery.
Mr Baquer Namazi, who checked into the Cleveland Clinic in Abu Dhabi on Wednesday, was expected to undergo a carotid endarterectomy to clear out a severe blockage to his left internal carotid artery to reduce the risk of a stroke.
Instead he will receive alternative treatments recommended by the Abu Dhabi medical team.
His release comes as Iran faces new sanctions for cracking down on major protests triggered by the death in custody of Mahsa Amini, a young woman accused of violating rules on covering her hair.
Neda Shargi, the sister of Emad Shargi who is also held on espionage charges in Iran and was sentenced to 10 years in prison, welcomed the news of Mr Namazi’s extended release.
