Amnesty International has called on the Iranian authorities to drop all charges against the prominent journalist and human rights activist Emadeddin Baghi, following his release on bail on Wednesday.
The recipient of 2009's Martin Ennals Award for human rights, he had been detained since his arrest in December 2009.
He was released from Tehran's Evin prison on bail of 200 million Tomans (US$200,000).
Though released, he now faces additional charges of undertaking "propaganda against the state" and "colluding to commit acts against national security".
The charges relate to an interview he conducted two years earlier with a now deceased government critic and senior cleric, Grand Ayatollah Montazeri.
He is due to face trial on the new charges on 7 July. Several other cases are also pending against him. If convicted and imprisoned, Amnesty International would consider him to be a prisoner of conscience
"The release of Emadeddin Baghi is a small step towards ending injustice. Unfortunately hundred of others are languishing in prisons and Baghi may yet be returned to the infamous Evin prison where so many rights actitivists are held," said Hassiba Hadj Sahraoui, Amnesty International's Deputy Director of Middle East and North Africa.
"But Emadeddin Baghi has been repeatedly imprisoned and released for his work. All conditions of this release must be rescinded and the charges against him must be dropped."
Emadeddin Baghi was arrested the day after mass anti-government protests were held in Tehran and other cities during the Shi'a religious occasion of Ashoura, in December 2009.
A few days earlier, BBC Persian TV had aired an interview Baghi had recorded two years earlier with Grand Ayatollah Montazeri, to mark the cleric's death earlier that month.
Journalists have been subjected to a wave of arrests in Iran following the 2009 post-election demonstrations, often being detained in solitary confinement without charge or trial.
"The Iranian authorities' crackdown on journalists and human rights activists since the disputed 2009 election is a blatant, but doomed, attempt to repress all criticism and cover up a litany of abuses," said Hassiba Hadj-Sahraoui.
"Iran must end the harassment of human rights defenders and the criminalization of human rights activism."
Over 100 journalists perceived as "reformist" are believed to have been arrested following the 2009 demonstrations. At least 40 of them remain detained, imprisoned or on temporary leave at risk of return to prison. Others are free on bail, awaiting trial.
There are frequent reports of further arrests, and the banning of publications.
During a previous period of imprisonment in 2007-2008 prison officials delayed granting Emadeddin Baghi urgently needed medical treatment.
He was eventually granted medical leave, but he still suffers from kidney, bladder and other problems arising from the treatment he suffered. Before his release in 2008, Baghi suffered three seizures and a heart attack.
Baghi has been repeatedly arrested and imprisoned for his work as a human rights activist and journalist in Iran. His imprisonment in 2007 came after being found guilty of "printing lies" and "endangering national security" upon the publication of his book, The Tragedy of Democracy.
He also spent three years in prison between 2000 and 2003 after being convicted of “acting against national security” for his writings about what became known as the serial murders of dissident intellectuals in Iran in the late 1990s, which the government later attributed to “rogue elements” within the Intelligence Ministry.
As well as the Association to Defend Prisoners' Rights, Emadeddin Baghi also founded another non-governmental organization, the Society of Right to Life Guardians, which campaigns against the death penalty in Iran.