A group of 17 Iranian political prisoners, including journalists and student activists, have been on hunger strike for a week demanding better treatment, opposition websites reported on Monday.
"So far five of the hunger strikers have been taken to hospital and the condition of the others is worsening," reported Kaleme.com, the website of opposition leader Mir Hossein Mousavi.
The group including reformist journalists Bahman Ahmadi Amoui and Keyvan Samimi as well as leading student activists Abdollah Momeni and Majid Tavakoli, "went on hunger strike after being transferred to solitary confinement and in protest at insults and humiliation," the website said.
Another opposition website Rahesabz.net said the hunger strike was triggered by an argument between some prisoners and wardens over the treatment of their families who had come for a visit on July 26.
Those on the hunger strike have been in jail since they were rounded up in the wake of protests that followed the disputed June 2009 vote which saw President Mahmoud Ahmadinejad re elected amid allegations of widespread fraud.
The authorities heavily cracked down on critics, rounding up scores of journalists, rights activists and reformist politicians.
Many of them have been sentenced to varying jail terms on charges of harming national security and provoking unrest. At least 10 have also been given death sentences.
Several prisoners detained in connection with the protests have reportedly embarked on hunger strikes at various times over the past year, among them acclaimed film director Jafar Panahi, with demands ranging from immediate release to access to lawyers.
Panahi was released on bail in May after three months in detention and several days on hunger strike.