Ahmed Shaheed told the UN Human Rights Council in Geneva that his repeated requests to visit Iran have so far been denied.
Among the violations he cited were the arbitrary arrest of journalists, harsh sentences for human rights lawyers, and cruel forms of punishment.
He said there were 200 executions in Iraq during the first 9 months of 2011, but 670 by the end of the year.
The 47-nation council appointed Shaheed last year against strong objections from nonmember Iran and its allies on the council.
Several European members of the council and the United States welcomed Shaheed’s report on March 12.
But Cuba and observer countries such as Sri Lanka, Syria, and Belarus criticized the report and called for Shaheed’s post to be abolished.