The human rights organisation Amnesty International says the human rights situation in Iran is now worse than at any time during the past 20 years.
In a new report Amnesty details what it says is a pattern of abuses before and after the disputed re-election of President Mahmoud Ahmadinejad in June.
Iran has dismissed previous criticism of its human rights record, with
officials saying that such criticism is politically motivated.
Thousands of people were arrested and dozens killed in Iran after the disputed election of Mr Ahmadinejad led to the largest street protests since the 1979 Islamic Revolution.
Dozens have been given jail terms, and prosecutors say at least five people have been sentenced to death.
'Burned with cigarettes,' student claims
Amnesty International cites the account of 26-year-old computing student Ebrahim Mehtari, who says he was accused of "working with Facebook networks" and protesting against the election result.
"They frequently beat me on the face," he is quoted as saying. "I was burned with cigarettes under my eyes, on the neck, head... They threatened to execute me and they humiliated me."
After five days he signed a false confession and was taken out and left in the street, still bleeding and semi-conscious, Amnesty says.
In August, defeated presidential candidate Mehdi Karroubi said some protesters detained after the election had been tortured to death in prison and others had been raped. Iranian officials denied the rape claims, but admitted that abuses had taken place.
Amnesty accepts that the Iranian parliament and judiciary have established committees to investigate the post-election unrest and the government's response, but says the mandate and powers of the bodies are unclear.