Dissident Iranian journalist Akbar Ganji has returned to prison after going missing for three days.
Mr Ganji has criticised upcoming elections since leaving jail
He told reporters as he entered Tehran's Evin prison that he would resume his hunger strike.
Mr Ganji was given temporary medical leave from jail at the end of last month; the authorities said he should have returned to prison on Wednesday.
He was jailed in 2001 for linking some senior figures in Iran to killings of political dissidents in the 1990s.
Mr Ganji returned to the prison alone on Saturday, carrying a hold-all and a bag of medicines, Reuters news agency reported.
"Now that I have gone back to prison, I will resume my hunger strike," he said. "All political prisoners must be freed."
He was granted temporary home leave on 29 May to have medical checks for asthma and back pain after going on hunger strike in protest at his lack of treatment.
He disappeared on Tuesday evening, after going out with friends. That same night, during his absence, judiciary officials arrived at his house with a warrant to return him to prison.
Tehran's hardline chief prosecutor said he had evaded arrest and was on the run.
In a letter distributed to the media through his wife on Friday, Mr Ganji denied he had gone into hiding or had done anything wrong.
He accused the Iranian authorities of not keeping their word, and turning down an extension to his home leave.
Mr Ganji suggested the reason they had tried to re-imprison him was because he had spoken to the press after his release.
Upon leaving prison, Mr Ganji was extremely outspoken in his criticism of Iran's clerical system of government.
He said that voting in next week's presidential elections would help Iran's supreme leader Ayatollah Ali Khamenei legitimise what he described as his personal dictatorship.