BERLIN - A group of independent experts appointed by the United Nations Human Rights Council called Friday for Iran to release all people detained during recent unrest. They said they are “shocked” by reports that suggest prisoners are being tortured or otherwise abused.

In a joint statement issued by more than a dozen of the human rights experts, the group said that of an estimated 200,000 people who took part in recent protests in Iran, some 7,000 are believed to have been arrested and that thousands remain in detention.

“We are shocked at reports of the ill-treatment of those detained,” the experts said. “Reports suggest that detainees are being tortured or are suffering other forms of ill-treatment, sometimes to extract forced confessions.”

They added that prisoners are being held in overcrowded centres and some are being denied medical treatment, according to reports.

The experts said that at least 304 people are thought to have been killed in the protests, citing “credible sources,” and criticized “the reported use of excessive force by the Iranian security forces.”

Noting that the government in Tehran has said the protesters will face severe punishment, the experts urged Iran to “ensure that all of those accused of crimes go through court proceedings that adhere to international fair standards.”