Hossein Fereydoun, the brother and close advisor of Iranian President Hassan Rouhani, has been transferred to hospital on his second day of detention, according to Iranian media reports.
Fereydoun was summoned for questioning on Saturday in a corruption case. He was later detained when he could not post bail, which was set at more than 15 million US dollars.
Fereydoun is a senior diplomat who took part in the talks that led to the 2015 nuclear agreement between Iran and world powers. Some Rouhani supporters have interpreted the charges against him as a move by the hardline judiciary to discredit the president.