The Associated Press
The many allegations came from family members, lawyers and released detainees, said Manfred Nowak, an independent investigator appointed by the U.N. Human Rights Council in Geneva.
"I truly believe that these complaints will stand up to scrutiny," he told The Associated Press.
The alleged abuses include holding people incommunicado and extracting confessions through torture, Nowak said.
One defeated reformist presidential candidate, Mahdi Karroubi, said Sunday he has received reports from former military commanders and other senior officials of male and female prisoners being raped by jailers.
Nowak said he has asked the Iranian government to investigate the claims and send him a report, but he has yet to receive a satisfactory response.
"If someone appeals to the United Nations claiming they were tortured, then the government is obliged to investigate the claims thoroughly," said Nowak. "To date, I'm unaware of any such investigation."
Nowak, an Austrian who has also investigated alleged abuses at the U.S. detention center at Guantanamo Bay, said Iran has not allowed him to visit the country.
Iran's mission to the U.N. in Geneva declined comment, saying communications between the government and U.N. experts were confidential.
There were allegations of torture in Iran's prisons even before the elections that resulted in a second term for President Mahmoud Ahmadinejad, Nowak said.
"I'm really concerned about the situation in Iran," he said.
