Iranian dissident Mehdi Khazali, who was serving a six-year prison sentence for acts against national security and spreading propaganda against the regime, has been freed on health grounds.
The official IRNA news agency quoted Khazali's lawyer as saying that the 48-year-old inmate was hospitalised after going on hunger strike, and that the authorities had decided he was too ill to return to jail.
"A representative of the prosecutor and a doctor went to my client's bedside and have judged that the continuation of imprisonment would be dangerous for his health," said lawyer Mostafa Tork-Hamedani.
"He is free," he added.
Khazali was arrested on January 9, 2013 for the third time in two years and released on bail in June the same year. But he was arrested again last month and sent to jail to serve his sentence.
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A doctor by profession and a veteran of the 1980-88 Iran-Iraq war, Khazali is the son of Ayatollah Abolghassem Khazali, an important religious figure known for taking ultra-conservative positions.
Ayatollah Khazali has disowned the views of his son, including his criticism of Iran's human rights situation.
The younger Khazali regularly criticised former president Mahmoud Ahmadinejad in a personal blog, but also on the BBC's Persian service and Voice of America (VOA) radio, which are banned in Iran.
Khazali was also arrested in 2009 for taking part in a protest against the controversial re-election of Ahmadinejad.
Many reform-minded activists, journalists and human rights campaigners have been arrested in Iran in recent years.
Fifteen dissidents were pardoned last September, a month after President Hassan Rouhani took office on the back of an election win which had the support of moderates and reformers.
Rouhani had promised political reforms and a more moderate cultural policy, but the backbone of his victory was a pledge to improve the economy, which has been laid low by international sanctions imposed on the Islamic republic because of its disputed nuclear programme.